Are you a hosting customer or an admin? Because thise forum is only for support to DA license holders, so admins, not for hosting customers. They should ask support at their host.
In this case, looks like php is not parsing, can have any reason.
If you're an admin, check your /var/log/httpd/access_log and error_log and your /var/log/httpd/domains/domain.com log and error log.