[kh99]

You must have changed a php file. If you don't have any other changes to the vbulletin files you could just upload the files again and overwrite the existing ones. If you do have other changes you don't want to overwrite, then maybe look at the file modification dates and see what you changed.

You could also use a plugin, but you didn't mention that. If you think you might have created a plugin then you can disable them by editing includes/config.php and temporarily adding this line (near the top just under <?php):

define('DISABLE_HOOKS', 1);