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.com/kb/Basic+Troubleshooting#w_8-make-a-new-profile

If that new profile works then you can transfer some files from the old profile (if it is still there) to that new profile, but be careful not to copy corrupted files.

See:

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

I have tried creating a new profile however when when I use Terminal to open the Profile Manager, the same message of "Your Firefox profile cannot be loaded. It may be missing or inaccessible." still comes up.

Any other suggestions?