This article should help - https://support.mozilla.com/kb/Lost+Bookmarks

Firefox tries to keep bookmarks when you update it. If however you use the option saying something like "delete settings" it will delete all settings and profile detail for all installed versions of firefox. If you still have bookmarks on Internet Explorer, you could reimport them again. It is sometimes possible using recovery software to get bookmarks back that have been deleted see this [https://support.mozilla.com/en-US/questions/787020 thread] <-- clickable link -- ''"I deleted by mistake bookmarks by uninstalling the previous version of Firefox beta 4.011b... Is there anyway to recover them?"'' See also * [[Backing up and restoring bookmarks]] - remember to make manual backups of your bookmarks, it is easy to delete or overwrite the files *[[lost bookmarks]] - sometimes they are not totaly lost * [[importing favorites and other data from Internet Explorer]] - in your case even if they are out of date it may be the easiest and best option to try