That's what I asked for ...a TUNEUP. The reason: Better than fifty percent of the time I would get a message stating that that site could not be found.
What did I get? My toolbar is gone. I did not get my lower search bar back. My browser is gone . In it's stead, I got "google". What ever would possess you to shack up with google. I signed on with mozilla to get away from google. I hate google. It is invasive and omnipresent. My bookmarks list is gone. It was replaced by a poor substitute for a neon marquee with a info bar streaming across the page.
Come on people. I'm as analytical as they come. A bomb going of beside my wouldn't solicit more than a mmm, until I could think about it for a bit. But this, are you trying to get rid of me. Have I offended you in some way.
I saw the extensive list of suggestions for you to do/correct and I did not see any of this, anywhere in that list. Might I suggest that someone seek employment elsewhere.
A tune-up is also known as a Refresh: Refresh Firefox - reset add-ons and settings. When that works correctly, you don't lose your bookmarks, so it sounds like something went very wrong.
Normally, Firefox moves your entire profile folder with all of your settings and data to your desktop inside an Old Firefox Data folder.
Can you find that folder? Hopefully, yes, and then we can suggest next steps. This thread has one approach: https://support.mozilla.org/en-US/questions/1322197#answer-1384732
If you do not have the folder, the Refresh might not have completed. I can suggest next steps in that case.