Error Establishing a Database Connection

Help! I’m in the middle of a new product launch and I’m getting this message when me and others try and visit our website:

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 clo1023111352658.db.3947150.hostedresource.com. This could mean your host’s database server is down.

What do i do to fix this? couldn’t be worse timing…