After doing what Rob Day described above the program will go back to its defaults. This will mean that you will have to recreate any of the customization that you might have done. To protect yourself in the future, I would suggest that after you've re-set up the program to the way that you like it (do this with no document open) quit the program. This will "lock in" all your new preferences. Then I strongly recommend making a copy of the new preference folder (it's the new version of the one you earlier trashed). If you ever need to reset preferences again then you can replace the corrupted preference file with the pristine version that you "put away for later". When you reopen the program after that all will already be as you need it to be.