Edit config.php file and add a line:
$CFG->auth='manual,email';
No need to restart any service, just attempt to login.
Once logged on as an Admin level user, enable what you turned off. Re-edit config.php and just comment out the line above by placing // in front of it. Now looks like:
//$CFG->auth='manual,email';
Think I'd leave the line there for a while until you get the user authentication worked out for your site.
Note: always keep 2 users (at least) with 'manual' - two users that are admin levels. You might want to create another account where you know the login/pass and set it to manual and admin levels.
'spirit of sharing', Ken