Hello Sandy.

That probably happened because, when uninstalling the beta version, you ticked the box that said "clear private data as well", or something along that line. That is a big problem if you used the same Firefox profile for the beta as you did for your day to day version. A very big problem, because what you just did was delete it.

For good, I'm afraid.

Please read this for more information on profiles. You may also want to learn about managing profiles and all that, just follow the link:

http://support.mozilla.com/en-US/kb/Profiles

It doesn't matter if you use separate profiles, if you tick to remove personal data then all Firefox profiles will be removed. So never use that choice when uninstalling, unless you really want to remove all Firefox profiles.

You can try if you can recover a JSON backup with an undelete utility like Recuva.

You should backup your profile data to avoid such losses. See http://kb.mozillazine.org/Profile_backup and Back up and restore information in Firefox profiles

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