I have no idea how it affected your theme, unless you accidentally made some other change to the config.php file.
Here's what to do: login as admin and go to Site administration -> Users -> Permissions -> User policies and reset the Default role for all users back to Authenticated user.
Then edit config.php, removing the change I gave you.
Better still, if you made a backup of config.php before making the change, simply overwrite config.php with the backup, restoring it to exactly what you had before.
Edit: I see you already did what I suggested