Hi, assuming you are referring to bookmarks: First open bookmarks > Show All Bookmarks > Import and Backup > Restore, and see if you have a backup there.

If not, please see - Profiles - Where Firefox stores your bookmarks, passwords and other user data, and Recovering important data from an old profile.

If your question is resolved by this or another answer, please take a minute to let us know. Thank you.

Did you refresh/reset Firefox?

When you reset Firefox then a new profile is created and some personal data (bookmarks, history, cookies, passwords, form data) is automatically imported and the current profile folder will be moved to the desktop to an "Old Firefox Data" folder. Installed extensions and other customizations (toolbars, prefs) that you have made are lost and need to be redone.

It is possible to recover data from the old profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• https://support.mozilla.org/kb/Recovering+important+data+from+an+old+profile
• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Are there any compressed .jsonlz4 backups in the bookmarkbackups folder in the current profile folder?

• https://support.mozilla.org/kb/restore-bookmarks-from-backup-or-move-them