Do you have an "Old Firefox Data" folder on the desktop in case the Refresh feature in Firefox has been used and a new profile has been created? *https://support.mozilla.org/en-US/kb/reset-firefox-easily-fix-most-problems You can also check if you have an orphaned profile that isn't registered in profiles.ini and that does not show in the Firefox Profile Manager. You can check that by opening the current profile folder via the about:profiles page and go up one level to see if there is only one profile listed. *http://kb.mozillazine.org/profiles.ini_file If you have found an orphaned profile then you may want to recover some personal data. You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the <b>about:profiles</b> page. *Help -> Troubleshooting Information -> Profile Directory:<br>Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder *http://kb.mozillazine.org/Profile_folder_-_Firefox ---- You can copy files like these with Firefox closed to the current profile folder to recover specific data. Note that you should be cautious with copying SQLite database files if you previously had problems. *bookmarks and history: places.sqlite *bookmark backups: compressed .jsonlz4 backups in the bookmarkbackups folder *cookies.sqlite for the cookies *formhistory.sqlite for saved form data *logins.json and key3.db (decryption key) for Passwords saved in the Password Manager *cert8.db and possibly cert_override.txt for (intermediate) certificates stored in the Certificate Manager *persdict.dat for words you added to the spelling checker dictionary *permissions.sqlite for Permissions and possibly content-prefs.sqlite for other Site Preferences *sessionstore.js for open tabs and pinned tabs