When you used cpanel to load your site, it automatically created a database a username a password to match, what you need to do now is goto your cpanel and select MySQL on that page you need to create a new database user with a password. Then you need to give that user access to the nuke database.

The reason is you deleted the orginal config.php file ?

So when you do the above you need to open the config.php and put whatever username and password you setup, you with me ?