Item Gone

I log off for the night, all items on my character. I come back the following morning and my amulet is gone. It's the only thing that is gone. It was a mid-grade amulet, nothing special but it's the only thing that is gone from the character.

I dunno what else to say. I can't track what happen to the item like you can from guild transaction. Why would this one piece of gear vanish? I've read other players have had similar situations happen where stuff is missing.