Delta customer service cannot address lost and found issues if your item was lost external a plane or gate. In such cases, you would have to contact the airport or, if the item was lost in security, the TSA to file or follow-up on a claim.
Customer support also can't assist when a passenger doesn't have appropriate identification to fly: Issues around passports and government-provided IDs ought to be settled before arriving at the airport.

Delta Airlines Office Hanoi
Delta Airlines Office Hanoi