They moved the mySQL servers which caused a lot of people problems.
This you should be able to fix yourself.
You should have a config , configuration , settings .ini or .php file for your blog etc. Open it up and make sure the database host is set to 'localhost' . If it is not, change it.
If that does not work, go to cPanel, then mySQL Databases and drop the database user from the database (do not delete him, just drop him from the database). Then add him back, making sure to check "ALL" when the pop up page asks you to set the permissions.
If that does not work, post back here.