It’s down because your website is using SitePro and SitePro was removed almost a year ago.
The are the relevant announcement topics:
The only way to get your website back is to do what you should have done a year ago: migrate to a supported website platform. I don’t know if you can still get your website content back. We kept the builder running for almost a year after it was officially removed to help make that easier, but that window has closed now.