If this is a problem on all browsers, I'm afraid that the Windows update may have permanently removed that data from your computer. Unfortunately, this is a problem that's more common than it should be.

If you go to the %appdata%\Mozilla\Firefox\Profiles folder on your computer, you can check to see if your old Firefox profile still exists there. Sometimes, it may also be moved to a folder called Old Firefox Data on your desktop.

In some cases, the Recover lost or missing Bookmarks article can also help fix the problem, if the data is still on your system.

Sometimes Windows will create a folder called Windows.old (or something similar) on your hard drive. Occasionally that folder may contain your Firefox profile folder in there somewhere.

Hope this helps.

The issue is resolved, but not sure why. When update to 1909 occurred, got "The user Profile Services service failed the sign-in. User profile cannot be loaded". I was stuck here and had to shut down my computer. When I restarted the computer, it booted up why no issues, but all my Windows and browser settings were gone. After a few hours trying to recover, I gave up but I decided to do a restart. Miracle of miracles, this seems to have reset everything. I couldn't find the profiles originally, but after the restart, they were back. I have now taken the precaution of exporting my bookmarks to HTML in case I ever need to restore them again.

Thanks for your input.

Did you look for a C:\Windows.old folder that could possibly have a backup?

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile