I'd just read the end of the story to R- (and was told that I'd written past the end, which is always a risk when you're tired and pushing), saved, and then wanted to back up to an external source, a nice little USB stick in this instance, before going to bed. So I closed the file in Word, went to my directory shortcut, and looked for the file in its proper subfolder.
Only to find that the "last modified" time for the filename there was 1:30 in the afternoon, not 11:59 at night. Opened the file, thinking exactly the S-word you're thinking of, and sure enough, none of the work done after that was in the file. About, oh, 2200 to 2500 words were missing. (Yes, yesterday was a 5000+ word day.) Panic. Anguish. Miseries. And, at midnight after a very long day (several days) I wasn't able to think of any way to recover it. I knew I'd saved repeatedly all afternoon and evening, including that final save...how had it gone wrong?
I quickly posted on my sff.net newsgroup (where I get fast useful responses) and started trying to reconstruct as much of the missing material as possible, checking back to the newsgroup every few minutes to see if someone had an idea. To save you worry...yes, someone had the right answer. For its own idiot reasons (which in this case included a power blip while the file was open in the early afternoon) Word had decided to save the restored file to a different directory, much higher in the tree...and though I'd looked there, I hadn't realized that that directory was organized by time, not alphabetically...so I hadn't found it.
I'd rewritten close to 1000 words by the time I found the real thing again. They weren't, for the most part, as good as the original (I was too tired and too upset to get into flow) so I happily overwrote them when I copied the real thing to the place it should've been all along. The real thing now exists on the USB stick drive and in two places on the main computer.
I'm tired this morning (late nights are not good for natural larks) and I'm going out with the camera to recover my balance and get the kinks out of a body that has spent far too much time at the computer this week. But I'm much relieved. Yesterday's writing had included not only first drafting toward the end, but quite a bit of editing/revisions on the story --expansion of scenes that someone had said were rough or felt rushed, transition smoothing, cutting stuff that was extraneous, fixing clumsy wording, continuity fixes, "fossils" of earlier drafts where things had been changed since, the kind of thing that is time-consuming to reconstruct and that is easy to miss on a fast re-work. The real thing wasn't perfect (yet) but it was the closest to final that I had. SO glad to find it again.
But really...I did not need this excitement.