media library photos – all sudden don't attach anymore?

without installing any plug-ins and without upgrading wordpress, suddenly all 300-400 photos on my website are a blue square with a white question mark!? AGH! does anyone know what happened.

the worst part is when i go in an hit “reattach” to the post it was going to, nothing happens and it remains the same blue question. but even if i were to go in an re-attach them all somehow, would this all happen again?

i hope there is a giant “restore” photos button.