Look on your desktop. Do you see a folder called; Old Firefox?

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

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible +++++++++++++++++++++++++++++++++++++ Type about:profiles<enter> in the address bar. How many profiles are listed? How many should be there?

You shouldn't be losing your personal data in the profile folder because of an update. You can check if you have orphaned profiles that aren't registered in profiles.ini in the location for the profile folders

• C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile>\

Note that "AppData" (XP: Application Data; Mac: ~/Library; Linux: ~/.mozilla) is a hidden folder.

• http://kb.mozillazine.org/Show_hidden_files_and_folders
• http://kb.mozillazine.org/profiles.ini_file

You can copy files like these to the current Firefox profile folder to recover specific data.

• bookmarks and history: places.sqlite
• bookmark backups: JSON backups in the bookmarkbackups folder
• SQLite files like cookies.sqlite (cookies) and formhistory.sqlite (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 and tab groups

Thanks for the replies. I did not have a file called 'old firefox' but I did find an old back-up of my bookmarks - importing this did solve all the problems.

Good work. You could restore your original profile using the instructions above.