database

when I try to open wordpress/index.php or install.php in my brwser, got this msg

We were able to connect to the database server (which means your username and password is okay) but not able to select the extreme database.

Are you sure it exists?
On some systems the name of your database is prefixed with your username, so it would be like username_wordpress. Could that be the problem?

– I’ve tried with username_wordpress (changd username) but still nothing