Pages not displaying correctly, content vanished

1. Switch to the default theme and see what you get then?
2. Did you recently make a new post and fill that one by a straight copy/paste from Word? Delete that post an dsee what happens?
3. Did you recently activate a new plugin? Deactivate it and see what happens.

Do you have short code? sometimes this does it. go to wp-includes/formatting and search for Line 174 or the like and comment it out with // it helped with my disappearing content. Oh, and don’t forget to note down where you change things in the wp core because you need to do it again and again with every update

$pee = preg_replace('/<p>s*?(' . get_shortcode_regex() . ')s*< /p>/s', '$1', $pee);
// don't auto-p wrap shortcodes that stand alone