Hi, m42folker, There are a few ways to fix this problem, here is a link https://support.mozilla.org/en-US/kb/recover-lost-or-missing-bookmarks to help you.

Did you previously create a backup of your personal data ? *https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles Were you previously using Sync ? Do you have a C:/Windows.old folder that can possibly have you personal data ? *https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile ---- You can check for issues with the <b>places.sqlite</b> and <b>favicons.sqlite</b> databases in the Firefox profile folder. *use the "Places Database" -> "Verify Integrity" button on the "Help -> More Troubleshooting Information" (about:support) page If errors are reported with "Verify Integrity", close and restart Firefox or reboot and retry.