Site and dashboard not working

Hi,

I upgraded to the new version of WordPress this morning, and then about 10 minutes later I also changed themes. Everything appeared to be working fine but about 15 minutes later my whole site crashed. I can’t even get into my account anymore (by logging in at http://www.sweatlikeapig.com/wp-admin).

This is the message I receive:
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?
If you’re unsure what these terms mean you should probably contact your host. If you still need help you can always visit the WordPress Support Forums.

I have checked with my host and their server is operating fine. From reading online, I understand that if I delete my new theme the problem should fix itself, but how do I do that if I can’t even log into my account?

It would be greatly appreciated if someone could reply as soon as possible. Thanks in advance.

Tara