I recently messed with the privacy and security settings in an attempt to a get a website working on firefox. In the process I must have changed something which now causes to default search engines and bookmarks to disappear every time I start a new session. When I launch firefox in troubleshoot mode or use the refresh option, it works but only temporarily because once I exit and launch firefox again, I'm back to no search engine. I've deleted and reinstalled firefox, i've removed .sqlite and .json and meta data files. Everytime, I do this, it resets my browser to it's default state (but with me being signed out of course) so once I sign in, I'm back to no search engine. Bottom line the problem will remain so long as my profile is set the way that it is and I don't plan on deleting anytime soon so if anyone knows how to reset your firefox account, like start it from scratch, would really appreciate it