Do you know your userid?
If so set it as the Super Admin and nobody else.... in the config file.
Next if you still can't login then reset your password via phpmyadmin, here an incrypted password for "admin"
replace the password for your account in the user table of the database.
PHP Code:
5de5a1e8a825ff8f12693882b2422c2e
Then see if you can login, if you can then change that password via the admin panel.
Next I would re-upload all original vbulletin files. See where you are at from there.