Hi and welcome to the forums 
Immediate point - do not pick up/destroy the chest, or put anything else in it.
It sounds like you’ve been hit by a recent bug caused by the database not loading completely after a restart. The good news is, if it is the same bug, your stuff should still be ‘there’ just in kinda limbo. A restart of the server should, in theory, cause the missing items to reappear.
I hope it is that bug, since it seems everyone who’s lost stuff to this bug has got it back at some point. Funcom are working on a fix. See below for more info