You can check for problems with the places.sqlite database file in the Firefox profile folder.

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox
• https://support.mozilla.org/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file

• Places Maintenance: https://addons.mozilla.org/firefox/addon/places-maintenance/

Not only did this not fix my problem, it made it worse.

In addition to multiple instances of the Bookmarks Tool Bar folder, i now have multiple instances of 90% of my bookmarks.

Apparently uninstalling Firefox doesn't solve the problem either. I tried that. Not only did all my original bookmarks come back, so did all of my add ons. Obviously, the uninstaller leaves a bunch of junk behind.

What exactly did you do from the suggestions in those articles?

You may have to restore an older JSON backup if the most recent backup that gets restored is already corrupted.

The name of a JSON bookmarks backup file includes a total item count (includes folders and separators) and an hash value to prevent saving the same backup more than once.

• bookmarks-YYYY-MM-DD_<item count>_<hash>.jsonlz4