Sorry you have issues. Sorry I do not have much time. ( _{Potentially bug 1243549 related see for example my post [/questions/1110662#answer-846478]} ) I will try to get back to this at some stage. I only have time now for a brief comment Use Internet Explorer if necessary Meanwhile try to immediately make a copy of your Firefox profile. Do that without restarting Firefox if it is not already running. I am trying to make sure any info relating to open tabs is not destroyed. Once the profile is saved, you can use Firefox again. Renaming prefs.js should be a temporary solution, but has (reversible) consequences. I am not too sure what we can get back, possibly partly by using Windows previous versions. Please give some indication of what you have lost, how important it is, and how much effort you are prepared to make to investigate and attempt recovery. No point in wasting your time and boring you with details if you have lost nothing important or have no time to try to recover what is lost. Initially See * [[Back up and restore information in Firefox profiles]] * [[Recovering important data from an old profile]] We should be able to at least get back with minimal effort the Open tabs as they were at a previous Firefox update. Bookmarks as they were a day or so go. History recovery may depend on Windows copies of places.sqlite