When something like that goes wrong, there is a helluva lot of trouble to go to to get it resolved. Firefox can break in numerous ways and yes it does take time to fix. People often make the mistake of uninstalling and reinstalling but the same old broken profile gets retained, unless you follow the detail for removing it (and backing it up).
Perhaps your quickest solution would be to create a new profile, then migrate your bookmarks, etc. from one to another.
I've been in chat and it is very nice and works well! It sure would be worth it. As an alternative, you could get an additional browser, if you don't want to spend time fixing Firefox.
What I would come back to though is if something is broken, then likely other things are broken too. Additionally, things tend to get worse instead of better. Personally, I would just fix it. It may take 10 mins. It may take an hour. From that point on though, you are good to go.