Did you check older backup in the bookmarkbackups folder as it is possible that the most recent backup(s) are already missing those bookmarks ? The name of an automatically created JSON bookmarks backup in the bookmarkbackups folder includes a total item count (folders and separators included) and an hash value to prevent saving the same backup more than once. You also see this count in the Restore menu drop-down list. That should allow you to choose a backup that has the lost bookmarks. *bookmarks-YYYY-MM-DD_<item count>_<hash>.jsonlz4. You may have to check for issues with places.sqlite. If you use Sync then best is to disconnect Sync temporarily during troubleshooting. This can be caused by a problem with the <b>places.sqlite</b> and <b>favicons.sqlite</b> databases in the Firefox profile folder. *use "Verify Integrity" button on the "Help -> Troubleshooting Information" (about:support) page If errors are reported with "Verify Integrity", close and restart Firefox or reboot and retry. See also: *https://support.mozilla.org/en-US/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file *https://support.mozilla.org/en-US/kb/fix-bookmarks-and-history-will-not-be-functional