5 PM: All (four) links to Pages are not visible anymore on the main page. I can view some using direct links, and open it via  link down the page, but no changes can be implemented.
6 PM: Single post are not visible anymore. There are only the latest one on the main page. The Admin Panel says there are still 4 Pages and about 160-170 posts, but you cannot see/edit them. If you want to, it says "nothing found". The Comments are still there in the Admin Panel, visible and edit-able.
7 PM: The main page content disappears. The Admin Panel says: 0 Pages, 0 Posts, comments are still there.
When it all started, I copied all files from server, but when I exported the base file it was only 1,69 MB or so - just the comments I believe. Any help appreciated.