erro msg

hi there i have some problems with my wordpress blog and i did not done any editing to the database or something but i get this error msg.

Error establishing a database connection
This either means that the username and password information in your wp-config.php file is incorrect or we can’t contact the database server at localhost. This could mean your host’s database server is down.

Are you sure you have the correct username and password?
Are you sure that you have typed the correct hostname?
Are you sure that the database server is running?

Can anyone help me out??