Hello Mariusz,
Sorry for the problem with your website. The server itself does not look like it's down, but the website files appear to be missing. My recommendation is that you restore a backup a soon as possible. You can request a Data Restoration through the Account Management Panel (AMP). You will need to work with our live technical support team for immediate assistance with this issue.
If you have any further questions, please let us know.
Kindest regards,
Arnel C.