Maybe your profile got damaged during the update. Do you have a backup? If not, backup what is left of the profile, then remove it and restart Firefox to let it make a new one, then exit Firefox and start copying files from the backup to the new profile, checking frequently to ensure that what you are copying is working.

You can check for problems with the localstore.rdf file.

• http://kb.mozillazine.org/Corrupt_localstore.rdf
• https://support.mozilla.org/kb/Toolbar+keeps+resetting

Create a new profile as a test to check if your current profile is causing the problems.

See "Basic Troubleshooting: Make a new profile":

• https://support.mozilla.org/kb/Basic+Troubleshooting#w_8-make-a-new-profile

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems.

If the new profile works then you can transfer some files from the old profile to that new profile, but be careful not to copy corrupted files.

See:

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