Are you using Firefox Sync?

• https://support.mozilla.org/kb/what-firefox-sync

You can try to repair the places database with this extension:

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

You can remove duplicates with this extension:

• CheckPlaces: https://addons.mozilla.org/firefox/addon/checkplaces/

See also:

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox

not running sync. ran the places maintenance addon and see no difference. This a a second PC I keep at the cottage. I think what I will do is transfer the bookmarks from my main PC and over write this one. Will post back with results.

It is probably best to delete the places.sqlite file and restore the bookmarks from a JSON backup that doesn't have the duplicates.
You may still find one in the bookmarkbackups folder.
Firefox keeps 10 backups, one for each day you start Firefox.

• http://kb.mozillazine.org/Backing_up_and_restoring_bookmarks_-_Firefox
• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox

Thanks. I am back in town for the week. I will take a copy of the bookmarks from home with me on Friday. I will also try the restore from backup and let you know how it goes as want to know how to do that option for future issues. Will not know results until Saturday so standby I will be back.

I was able to restore the file from one of the 10 backups. I had to go back about 5 to get one that was correct.

Thanks

You're welcome