Lost items from inventory
Oh god, I thought I was going crazy. My AC tokens and my spanking new rare shoulder disappeared after I unequipped during CoF Path1 (those fireballs).
How does one go about informing Anet?
You can open a support ticket at the support site support.guildwars2.com
But you should know Anet’s standard policy is (outrageously) not to restore items lost through bugs.