If you are talking about a word doc. or any other such document like that, then your chances of recovering it are very slim.
An excellant program is File Scavenger 3.0 which I have used a hell of a lot.
Now depending on whether you have turned the PC off since then, if you go to select all view files, and go to the folder where you have saved the file, then you may be lucky and see a list of temp files, (they will be translucent and not solid and often have a $ sign in them) it would then be a matter of going through each one and seeing if it still exists in there.
This is a remnant of Microsoft office autosave feature, as it sometimes leaves a copy of each time it has been autosaved.
Other then that mate I don't think there is much else that can be done.