Firefox Support Forum

So a few weeks ago I finally upgraded to 49 something. Bookmarks worked normally after the upgrade. But yesterday my computer froze and I had to reboot. Bookmarks and history suddenly missing, can't create bookmarks. Found Restore, can see a list of backup bookmark files with dates and file size, but get message "unable to process backup file." Browsed for possible solutions. Ascertained that I only have the one profile. Downloaded 50.0, installed, rebooted. Still nothing. I did not install any new add-ons as far as I know. Not doing any syncing. (By the way, I view my bookmarks as a sidebar.)

What to try next?

Dell laptop, Vista.

The Firefox update that rolled out on Nov. 15, 2016, seems to have deleted both my browsing history and bookmarks. How can I restore these (especially history, which is way more important to me)?