Is Firefox gone, or just not starting? '''https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible'''

After you create a new profile, we can help you recover data from the old profile. This article describes the most valuable contents if you want to give it a try first: [[Recovering important data from an old profile]]. Your old profile should be in one of the following places: (1) On your desktop, inside an Old Firefox Data folder (2) In its original location, inside the Firefox Profiles folder To find #2 if needed, starting from your new profile, either: * "3-bar" menu button > "?" button > Troubleshooting Information * (menu bar) Help > Troubleshooting Information * type or paste about:support in the address bar and press Enter In the first table on the page, click the "Show in Finder" button. This should launch a new window listing your currently active profile folder contents. Make a note of the profile name, then navigate ''up'' one level in Finder to the Profiles folder. Is there another semi-randomly-named profile there? If so, most likely that has your old data. Sometimes things may get confused when copying between folders so I suggest making a backup before you get started.