For items lost at the check-in counter, at the departure gate area or onboard the airplane, contact your airline.
For items lost in the passenger terminal of BKK Airport, go to level 4's Information Counter located close to doors 5 & 6, before KL /MN area. Or contact the call center at 1722 (from outside call +66 (0)2132 1888.
Lost Baggage Tracking Service Counter in on level 4 in the Departures Hall - between gates 5 & 6 (tel. 0-2132-1880, or e-mail: firstname.lastname@example.org