Error establishing a database connection

I tried logging into: https://www.amazingpicturesonline.com/wp-login.php

I get this message and can’t even go into WordPress:
Error establishing a database connection

Last night one of the moderators from ElegantThemes.com asked me for my WP login details so they could fix something on my site.

I believe it was the fault of the moderator who messed up my site and I can’t even get in to fix it. I even called Godaddy and they want me to pay $150 to restore my site.

How can I fix this if I can’t even login???