HELP- work lost for no apparent reason!!

HELP- work lost for no apparent reason!!

I was working on a document last night and when I came to access it this morning there are over 1000 words missing. I was saving regularly and made sure to save before I logged off last night but the last hour of saves has gone. PLEASE could anyone advise me??

I have tried reverting to previous saves but they are all correct, its just the last hour or so worth that is just vanished!!

VERY stressed!!