I lost some updates on the files I was working with, after a computer crash.

Thank you for this suggestion Megan, I did a search for three files as a test and found some "shortcut" files, but they were all versions from when I last opened them yesterday afternoon, i.e. without the saved edits. Still - I'll remember to try this next time immediately after the crash.

The file types are LibreOffice Writer and Calc (their equivalent of Word and Excel).

Finally, I realise it seems impossible that I saved the files, they synced, and then those versions somehow disappeared again from the version history and the events page. I guess it is possible that I am misremembering saving files on Tuesday afternoon/evening, or (less likely) that I did save, am misremembering checking that Dropbox had synced, and in fact it then didn't sync for three hours (though that would be a bit worrying, and as I said above, seems unlikely when it usually takes a few seconds after saving).

The problem is that the last time this happened, which I think was last Wednesday (the 5th), I woke up on the Thursday to find that *all* of my saved edits had disappeared. None of them were major, but my point is that it just doesn't seem plausible to me that I didn't save any files all day (my normal habit is to save whenever I get up from my desk) or that Dropbox didn't sync all day.

But again, I realise it's also implausible that saved versions are disappearing from Dropbox. At this stage, I think what I'm going to do is use an external hard drive as a secondary back-up, and do a three-stage check every time I save: save to my computer, check it syncs, then save to the external drive. That way, if there's another incident, I'll be able to say with 100% certainty what has happened.