Hello?

Hey this usually happens when Firefox creates a new empty profile after reinstall. Type about:profiles in the address bar and check if your old profile is listed, then open it and see if the bookmarks return. You can also try Bookmarks Manager, Import and Backup, Restore, and pick an automatic backup date if available.

Thank you, I tried this yet again (numerous profiles) but no luck.

I've used Firefox for years but never had this problem before and I'm very disappointed. I try to avoid using Google as much as possible but if I have to go through the inconvenience of trying to remember all my bookmarks I don't want to risk losing them again so will probably use Chrome instead.