Firefox updated yestarday. I see these changes: extension are gone, theme settings were switched from Dark to Light, "Startup -> Open previous windows and tabs" option went from checked to unchecked. These things are still fine: bookmarks, saved passwords and history. Tried reverting to older Firefox version, but it didn't help so I installed the new one again. I then checked profiles in AppData folder and I see three of them. The problematic one I just described, the one that was automatically created when I tried to downgrade to previous Firefox version and the one which only contains empty "parent.lock" file. There is nothing useful in "Extensions" folders (first profile has addblock extension file which I just installed, second profile has langpack extension file). I don't particularly care about which specific extensions I used since I can just reinstall them when I need them again, but one of those extensions contained custom written scripts which were running on specific sites to help me with my work. Those scripts are what I really want to recover.