I have been asked this many, many times.
The instinctive response is polite, short, but also defensive, and this often has the added bonus of leaving you feeling hurt and/or embarrassed. It may be that this is, nonetheless, the best approach as you won't need to go into too much detail.
However, there are a couple of other options which I would suggest:
(1) Be honest - tell whoever it is that it's taken however long, that it's bloody hard work, and that it hasn't done you any favours healthwise. Thank them for asking and for their support during this difficult time. You might be surprised by their reaction.
(2) If you are still enthused about your topic then plunge into that. Never mind how long it has taken - ask them if they know how 'x' relates to 'y'? You don't? Well, it's fascinating actually because... This tends to stop any follow-up questions from the person who was just asking for the sake of having something to say, and engages the person who is genuinely curious.

Beth,

So sorry to hear this. There are some case studies of students who failed PhDs and what happened next on the UCL website:
http://www.ucl.ac.uk/teaching-learning/training-development/phd-supervisor-development/phd_diaries
Scroll down and click on 'Failed PhD'.
These are true stories collected and anonymized by Professor John Wakefield (University of Lancaster).
It is possible they may give you some pointers.

Other than that, I can only echo the advice of others:
- talk to whoever you can to get advice and support- your supervisors, your department administrator, the person in your department responsible for PhD students, your student union, the University welfare office, University Chaplaincy/counsellors
- read all the official regulations incredibly carefully - was due process followed at every stage?
- go through the examiners' report with a fine-toothed comb - what were their grounds for this? Have they breeched any procedures?

I know the University may seem like your enemy now, but it is still in their interests (particularly if you were research council funded) that you come out of this with a qualification. Seek advice, prepare your case, and, if you can, go for the appeal. In addition, you could ask for a meeting with someone high(ish) up in the University - just requesting this might be enough to get you somewhere.

Feel like a complete and utter loser.
Am about to enter 5th year (full time - though I now have a full time job as well).
Applying for extension to funding body deadline on grounds of depression.
Just bumped into my potential external off to do someone else's viva.

Forgive me if I'm being daft but if all three sites are basically equally good and one site is enough (i.e. not the bare minimum but providing an appropriate scope for a doctoral study) then do you have to justify your choice any further than:
"There are eight possible sites. Of the eight sites, three possess these particularly interesting factors. This thesis will focus in site A. There would be value in testing the conclusions reached in this thesis in relation to sites B and C but that is not within the scope of this thesis (see directions for further research in the thesis conclusion)."
Am I missing the point?
I think this is sort of similar to a choice I have made whereby there is a big body of work produced by one author and I'm only looking at a specific set of works - not because the others aren't interesting or valuable, but just because a thesis needs to have a focus which is an appropriate size so that the material can be tackled at the right level of detail.
Does this help?

Ady - don't despair.
Or if you do, at least despair in company!
What's going on? I'm in a right state at the moment as well, but always happy to listen.

Two points (which sort of pull in opposite directions, but may help):
(1) My sup has actively talked me out of the idea of any "reveals". When I protest that this will make it boring, he says that thesis examiners aren't looking for a thrill, and, even if they are, they want to be thrilled by the quality of the work, not by a surprise twist. The number one thing they want is clarity, i.e. (a) this is what I'm going to do (b) this is me doing it (c) this is what I did. And each of these parts should fit together coherently so it's not a case of (a) this is what I'm going to do (or is it...? wait and see) (b) I was doing it but then something exciting happened (woo!) and then I went down a totally different road (c) look at where we have ended up - what a magical mystery tour!
(2) However, I think it is true that to achieve this coherence you have to be faithful to a certain extent to the shape of your research process. It needs to make narrative and logical sense.
So, what I would do in your situation is say (to give a mad example):
* In study 1 I tackle the question of why icecream vans make less money on rainy days. In the course of this study, as shown in chapter 2, I discovered that, contrary to the existing literature, the preponderance of pistachio icecream in vans is a contributory factor to the climate/profit relation.
* In study 2 I approach the question of why fast food vans at festivals charge £4 for a bottle of water.
* In study 3 I build on the discovery made during the course of study 1 regarding pistachio icecream, to compare nut-content, climate, location and profit in mobile catering.
Could this work? Give some sense of what happens in study 1 without going into huge amounts of detail, so that the question for study 3 doesn't appear to come out of nowhere.

Hi,
My heart leapt at your post because I am in pretty much exactly the same situation.
I have a very understanding academic friend who has made an arrangement with me whereby I am sending him what I write every few days. He's not reading it but if there's no email with a word attachment after a few days I get an email reminding me to keep writing. That has helped me to stop fiddling with one piece for ages or doing too much new reading, both of which were becoming a major problem.
Would you like to do some sort of check in thing where we could let each other know when we tick things off or get through a certain number of words? It might work in a similar way for you.
Also, as KB says, follow your rhythm. I find I can only produce good enough writing for a few hours each day (though I may need to sit at the computer just staring into space for quite a while first!). Then when my spurt's over, it's over and there's no point pushing into the night to get more out because it won't work. I'm sure I'll be doing that with revisions at the end but at the moment it's all about a steady pace.
I'll be thinking of you! You're not alone!

Given what you've said about the problem chapter...
I haven't finished writing my thesis yet but here's what I'm doing at the beginning regarding the things you've mentioned. NB - I'm doing lit phd as well and I think there is much more flexibility in structure than is the case with science phds.
In my (substantial) introduction I am going to review the literature on main author whom I'm studying. There isn't much of it (this person isn't very well known) and much of what there is is of a survey/biographical nature. I'm building on this work but doing something quite different so I will bring it in at later points in the thesis but I don't need to spend a whole chapter on it. Also in my introduction I will be outlining the broad field of the theory using which I am going to approach this author's work. This is to show I know that the theory is a big area with lots of different perspectives in it. I'll show I'm aware of how and when this theory emerged and how it's developed.
In my first chapter - my lit review/methodology, I focus in depth on the specific people from within the broad theoretical field that I want to make my main discussion partners. I show that I know their work and the secondary lit surrounding it and I flag up those things about their work which I want to take forward into the rest of the thesis and apply to the work of my particular author case study.
Then the rest of my thesis brings together these voices from the literary theory with the works of my author (hopefully!) to create some interesting and original thought.
From the advice I've had it's all about honing in (whilst nonetheless avoiding saying anything too banal and broad-brush stroke, e.g. 'Heart disease is a serious problem', 'Lots of people have thought books are worth studying'.)
So a Phd lit review on... lost socks... (!) might go like this:
(1) How long lost socks have been a problem (the invention of socks, washing machines etc) (competent ref-ing existing studies)
(2) The multiple existing responses to lost socks (emotional impact; physical impact; impact on sock design and washing machine design; lost socks as a literary metaphor, etc.) (competent ref-ing existing studies)
(3) This thesis focuses in particular on the interaction between individual emotional responses to sock loss and the development of cultural expressions - especially poetry - as a way of contextualizing this loss. The key voices in this debate are: Smith, Jones, etc. (really strong engagement with these studies)
(4) Building a methodology for discussing sock loss using the work of Smith, Jones, et al. - more precisely: what this thesis will seek to do; what questions will be answered; what resources will be brought to bear; what's missing from Smith and Jones that I will bring in from my own case studies and from Thompson's work on shoe loss... etc.
Is this any help? As I say, I haven't finished yet and other forumites should please correct me if they don't think this is the right approach.
The other thing I would suggest is reading as many other theses' lit reviews/methodologies as you can. I know you've looked at some but it can't hurt to look at more. British library ethos + google search for university e-theses should turn up loads of relevant comparisons.

I completely understand why you would feel like this - but I also think that this comment shows you are putting yourself under too much pressure.
If you decide before you begin to write that failure = the end of your meaningful existence then you automatically create a barrier that is incredibly difficult to surmount.
So, hard as it is, I think the first step you could take would be attempting to forge a different view of the situation. Don't deny your feelings - but also don't focus entirely on the negative things you feel about yourself and your work. Recognise that doing a PhD is according to one measure incredibly difficult (not many people do it with good reason) and, looked at another way, not so scary (it is evidence of learning, not evidence of having attained academic perfection; it is the beginning of being a professional researcher, not the culmination). Pay attention to other things in your life that give you satisfaction. Take time over these and show yourself that your life is not entirely composed of a Phd.
The other thing about putting pressure on yourself is that it makes it more difficult to hear any criticism - you catastrophise and see things as hopeless when it might not be all that bad.
The second thing is to address this issue with your supervisors. They may themselves be feeling a bit disheartened - perhaps they look back and feel they gave you the wrong kind of support in the past? However, it is emphatically (financially and professionally, never mind morally!) in their interest and your institution's interest that you complete your corrections successfully. Here's what I would do if I were you:
(1) Write down (if you haven't already) a list of exactly what you need to do. i.e. write out what your examiners have asked of you relating it clearly to work you already have; write down a plan for making these corrections (e.g. "to address this point I need to re-read Derrida's essay on 'x' and find further support elsewhere for point 'y'"); write down what the process will be when you have completed the corrections (e.g. in December I will resubmit the thesis to my supervisors/examiners - whatever it is you need to do).
(2) If you think that it would help to clarify things with your sups you could send these lists to them with an email which says 'This is what I understand I need to do. Please confirm that you are happy with this plan'.
(3) Seek out writing help from the university. Again, it's in their interests for you to finish, so email academic support people/postgraduate training people and find out if there is someone who can read through your work with you and help to tighten things up.
(4) Ask someone in the department who is not your supervisor or is another student to read through a small extract of your work as a favour and give you some tips.
(5) Ask your sups to set some specific meeting times to discuss your corrections. If they don't respond, talk to your mentor/head of department/postgraduate admin person/student union postgrad rep. Cast your net far and wide for help! Your sups have not done their bit until you are through the process as a whole - it's probably written into their contract that they shouldn't give you "significant supervision time" or something like that at this point but that does not mean you are not entitled to meetings about corrections where they give you clear advice and guidance.
(6) Talk to anyone and everyone involved in student welfare - you need a support network around you right now.
Hope things get better.

I think I am the worst phd student ever. Every single other person I know has completed.
I can't see any value or point in myself anymore. What is the point of all these targets and tick-lists? They may work for you guys but I just experience a series of failures. I've disappointed my parents and my supervisors so many times. I think that I work really hard. I am writing up and I write seven days a week trying to hit my deadlines. I never do. I can't face talking to my supervisor again. I can't do any better. I'm clearly just not cut out for this. I've made some bad decisions along the way I guess and I can't go back now. I can't quit. Then I'd have four years of nothing behind me. I don't want to go to the doctor because the only problem in my life is me and this thesis. I just don't know if I can stand this any more. Reading back through this message I can't see how to convey the extent to which I've failed. Really - imagine your worst nightmare about your own work. I'm running out of time and out of energy. I don't know why I'm posting this, but I have spent a lot of time looking at this forum over the years (while other people have passed and moved on) and I wish someone could just say something, anything, to help me see a way out of this.

I'm meant to be working at an exceedingly speedy pace these days, what with having run out of funding and having a sup who is enthusiastic about me finishing.
I set out with a goal of writing analysis of 8 sections of text today (building on some work I've already got but lots of new words too).
I haven't done one yet.
I've been procrastinating and crying all day.
Now I'm writing this public to make myself do it - COME ON! YOU'VE ONLY GOT A FEW DAYS LEFT TO FINISH THIS CHAPTER! GOOOOOOOOOOOOOOOOOOOO!:-s

Don't worry RG - you can do it! There's still time.
Spare a thought for slow coaches like me. My funding ran out in Nov and I'm still not done. Probably won't be until this summer.
Yep, that's four years full time. Feel like such a failure.
:$

Thank you so much for those replies. Feel much better just to have a different perspective on things.
About to go and kick start the work now (have got into this weird 11-8 working pattern) - the focus on submission rather than perfection thing is really good. I know my sup is focused on submission and he will tell me to leave this if I ask him. So I should just leave it and, as you say, do the background reading before the viva.
Thanks!

So, one of the people I am writing about in my thesis has two main areas of work (a and b). I'm just focusing on one of those areas (a) as that's the one that's relevant to my topic. However, the other area (b) isn't totally irrelevant and I've been bringing in bits and pieces to support my conclusions drawn from material in the area that I am focusing on. If that makes sense?!
I want to use concept 'x' which my guy has written about in area (b) in my discussion of area (a). Trouble is, unlike on the other occasions when I have referred to area (b), this time concept 'x' opens a whole can of worms. It is derived from another theorist whose work I've only the smallest knowledge of, and it raises loads of questions which I just can't answer within the scope of what I'm doing.
I feel really bad that I haven't researched the background to the idea more thoroughly - it was something I kept meaning to do but kept putting off as not the most relevant (or interesting!) bit. Now I'm out of time really as I'm writing up and my sup wants to see this work... well... yesterday.
Has anyone else had an experience where you want to use an idea but you don't have time or space in the thesis to go through all the ins and outs of it? - you just want to say, look that's there in the background and enables me to make this point, moving on...
I feel like I'm in deep trouble, like this is a big and unfillable hole and that my work just isn't up to scratch if I can still not know my sh*t at this stage! That's the main worry - why don't I know all about this? And what do I do as there isn't really time to fix it?
PANIC!

There's a long story behind this which I won't go into but basically I have recently been deprived of my main workspace. With less than six months left to submit.
I am now juggling spaces "on loan" from friends and colleagues together with using the library. I'm starting to settle into a pattern and it's not too bad, though I could do without the hassle. A continuing problem however is that I AM COLD:-(
If I were in my own house I could say, stuff it, I'll turn the heating up.
If I'm in the library there are some warm-ish corners to be found (can't work there all the time though, I just have too many notes and annotated texts to cart back and forth everyday - it wastes time and leaves me starting the day feeling frazzled).
When I'm using other people's space, and they have kindly said that they don't want me to contribute to any costs because it's only for a little while and they know I'm skint, I cannot bring myself to put the heating on.
I have multiple jumpers and fleecy jackets, a flask, and thermal undies!
But my hands get really cold and my woolly fingerless gloves are too bulky for typing. My face gets cold too.
My other half thinks I may have some sort of circulation issue, but the fact is I'm not going to sort that now, I'm writing my PhD and I just need to be able to get through the next few weeks. When I get cold I feel miserable and demotivated -it's really the last thing I need.
What do you think I should do?
Any innovative ideas for keeping warm?
(snowman)