W3 Total Cache Error

When I try logging in, I get the following error.

W3 Total Cache Error: some files appear to be missing or out of place. Please re-install plugin or remove /var/www/wp-content/advanced-cache.php.
Error establishing a database connection

The last time I posted was last week. Help please. Don’t know the version number for wordpress, but I don’t think it’s the latest version.