Whole site was deleted and replaced with standart welcome message

[KangJL]

Please read

My site and content has disappeared

Please have a look at the pinned topic. Your site was affected by an outage, and unfortunately your content was lost: If you have a backup or can restore the site via the database contents (which were left intact) you’re lucky, but if not, there is nothing that can be done but recreating your website from scratch.