Ali, do you know if a new profile was created when you reinstalled? Did you lose any other data such as history or bookmarks?

IF a new profile was created, then a possible avenue for password recovery is to find the files "logins.json" and "key4.db" from the old profile folder, and copy them into the new profile folder. These two files contain your logins and their associated information.

To try this:

• first you need to locate the new profile folder on your hard drive. If you do not know where your Profile folder is, see here: https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data
• next you need to locate the old profile folder. To find it you could try searching your harddrives for the file "logins.json", until you find a promising location for the old profile. (Note, by default Firefox on Windows stores profile folders in the following directory: C:\Users\<your Windows login username>\AppData\Roaming\Mozilla\Firefox\Profiles)
• close all running Firefox windows
• move the files "logins.json" and "key4.db" (if they exist) from the new profile folder to a backup location
• copy the files "logins.json" and "key4.db" from the old profile folder to the new profile folder
• restart Firefox

If this doesn't work, you can always close Firefox then restore the two files from the backup location.

Note, If you are missing other information from the old profile such as bookmarks etc., then see here for a list of other files that could be copied from the old profile folder to the new one, to restore this data (although once again, it's best to make backups of any files that would be replaced, and make sure that all Firefox windows are closed): https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile#w_your-important-data-and-their-files

An error message like XPCOM missing or about platform version or entry points not found can happen because of a failed Firefox update that left you with a mixture of old and updated files in the Firefox installation folder. This can happen in case security software was keeping a handle of some of the files in the Firefox program folder preventing Firefox from replacing all the files.

You need to reinstall Firefox and possibly remove the Firefox program folder to ensure that all files are replaced. You may have to disable security software temporarily in case the problem persists.

• https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

Reinstall Firefox:

• https://support.mozilla.org/en-US/kb/troubleshoot-and-diagnose-firefox-problems