If you haven't already, I would start with a normal shut down and restart of Windows.

If Firefox still can't start up, you can download the full installer to reinstall the program. Please see the steps in the following article: Custom installation of Firefox on Windows.

If you are looking on disk and you start with this shortcut --

%APPDATA%\Mozilla\Firefox\Profiles

-- there usually are multiple folders. The one whose name ends with .default-release (not the simpler .default) typically has the most data. When you reinstall Firefox, the installer should detect and use that folder, unless it is locked for some reason, in which case you might be forced to create a new profile.

Hey, thanks for your reply.

I didn't need to reinstall, as soon as I called it from the run prompt windows found it, so that was never a problem.

I did see that .default-release folder. It has 17 .jsonlz4 files. They are all from may and june. They are mostly gibberish.

I will reinstall FF now but I also just noticed that my TOR install is also out of whack.

Hi, So I went to Import Bookmarks, navigated to that folder you suggested and chose the last backup. There were all restored.

Thanks for your awesome help!

Glad you got it working. And lz4 is a kind of compression, so gibberish it definitely is if you don't decompress it first before reading.