Error establishing a database connection

Hey, I’m getting this error, when I don’t even go to log in, but to go to the page that I usually have to log in at:

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?

Why would this be happening?

Thanks,

Bryce