If you use the Time Machine or other backup then try to restore file(s) from this backup. *https://support.apple.com/guide/mac-help/restore-files-mh11422/mac You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the <b>about:profiles</b> page (Root directory). *Help -> More Troubleshooting Information -> Profile Folder/Directory:<br>Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder *https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data See also: *https://support.mozilla.org/en-US/kb/recover-lost-or-missing-bookmarks