Back when the new inventory system was introduced there were lots of bugs that led to missing data (weapons and such). When it was patched Disney had attempted to restore what they could, I personally had received all of my missing weapons back..
I would say it's unlikely they will restore it, but it's always worth a shot to try. I know if missing items were reported via the "Report a Bug" page around the time of the issue, they would in most cases be restored. Disney had considered charging for restoring Pirates, so I am not sure if they will view restoring an inventory item so late after it went missing as worth the time.
Would just get in contact with them using the normal methods and see what they can do.