Hi,
I’s simple.Delete your WP installation.Delete the DB associated with it.
Now create a new DB via phpmyadmin interface with any name you like.
No extract a new WP site in your www (if you’re on wamp) or htdocs (if you’re on xampp). Before browsing your new installation go get a copy of your wp-config.php and give it the DB name you just created and also the password.
Now browse your WP and go through the installation. You should be asked about the username and password. you’re done.
If there’s still something wrong, there shouldn’t.