I'm having trouble logging in to the Joomla backend. 

The only way I can access the admin panel is if I add `public $root_user="username";` to the **configuration.php** file. 

When I finally logged in, I tried changing the Global Configurations to set all ACL to their defaults so I don't lock myself out again, but I keep getting this message:

[![enter image description here](https://i.stack.imgur.com/oAUY6.png)](https://i.stack.imgur.com/oAUY6.png)

I've even tried adding a new Super User but then when I attempt to log in with the new user info it says the password is wrong or I need to make an account... not really sure what's going on at this point. Please help!