I want you to look a bit above that, where it says something like this:
define('DB_SERVER', 'localhost');
The reason is, while most servers run a local database server, some don't. In those cases, it can happen that the remote database server dies while the local apache is still running. Of course, even if you have database server running on a local machine with apache, it can still die while apache is still running ^^. It's just an application anyway.
Another possibility: apache can not connect to mysql server because of wrong username/password. Since you said that you didnt touch anything, I assume this is not the case here.
Anyway, without phpmyadmin or cpanel or ssh access to the server, all we can do is to wait for your host.