Broni
Posts: 56,041 +517
Reset Firefox: https://support.mozilla.org/en-US/kb/reset-firefox-easily-fix-most-problems
If the above didn't help...
Uninstall Firefox completely using this manual: https://support.mozilla.org/en-US/kb/uninstall-firefox-from-your-computer
NOTE. Use MozBackup: http://mozbackup.jasnapaka.com/ to backup your bookmarks and passwords. Do NOT backup anything else.
Install fresh copy.
If the above didn't help...
Uninstall Firefox completely using this manual: https://support.mozilla.org/en-US/kb/uninstall-firefox-from-your-computer
NOTE. Use MozBackup: http://mozbackup.jasnapaka.com/ to backup your bookmarks and passwords. Do NOT backup anything else.
Install fresh copy.