Have I been Hacked?
I do not know if the "New 100th version of Firefox" is real or a scam. I downloaded this new version and lost my History and Main Bookmarks. Have I been hacked?
Sometimes when the browser thinks there is a problem with the profile, it will create a new one.
Look on your desktop. Do you see a folder called; Old Firefox? Look inside. Look for the folder with the latest creation date.