Sorry to hear about that. Your old data should be in a folder on your desktop named Old Firefox Data. Can you find that folder? If you drill down into the old profile folder (name is semi-random, but often ends with default) and look for a folder named '''bookmarkbackups''' can you find a recent file named along these lines: bookmarks-2016-11-12_9876_''gibberish''==.jsonlz4 In that example, 9,876 bookmarks were backed up on 11/12/2016. If you have a good candidate for restoration to your new Firefox, this article has the steps: [[Restore bookmarks from backup or move them to another computer]] Note: the Restore menu might show one freshly made backup, but you likely need to use Choose File and point Firefox into your Old Firefox Data folder to find the one you want.