thank's for your fast support.
Knowledge root version was 1.02, now 1.03
The content is always visible.
That was the right hint => all values in table "files" "deleted" where set to 0
A SET deleted = 0 solved the problem
Sorry that I didn't see that yesterday.
Don´t ask me why this has happened . I'm sure nobody marked all attached file in every content as deleted.
I'll will keep an eye on it