Worn items dissapearing while playing

last night me and a friend were playing and his entire set of armor disappeared while exploring the volcano right off his character went from being fully armored to naked, dying and looting the corpse did nothing. After he logged off last night he had another set of armor, when he logged back in it was gone off his character as well as everything else but he was still where he logged out at. What is going on? this is a pve server #2725 so no one could have taken his gear.