A family of Microsoft word processing software products for creating web, email, and print documents.
This is a totally random observation that may help explain, or not. I've had the same issue (seemingly lost edits to documents) recently where I will be working on a document, but will do a "save as" (because I sometimes save each revision) and am prompted to select a folder. I select the folder and when it opens, where ever my curser is in the window, it will highlight whatever file it is pointing at and that same file name is auto-populated in the file name field at the bottom of the window. If I'm not careful and I hit "save" before scrolling to the correct file in the list or typing in the name of the file I'm saving instead of what is in the auto-populated field, the file will save and overwrite whatever file that the curser was on.
If you have the same scenario when you save, one suggestion is open the folder and open other files that are shown to be updated around the dates you were working on the document. It may have saved as a different file. It happened to me a couple times.