Foreigners who lose their passports while in Thailand must report the lost passport at a local police station before submitting a request to their embassy to get a new passport.
Supporting documents for making a request to the embassy are (a) a copy of the notification from the police station, and (b) a copy of previous passport with personal information and photo (if any). When the new passport is received, the foreigner will need a letter from the embassy to the Immigration Bureau to request cooperation from the Immigration Bureau to provide a new arrival stamp on the new passport of the foreigner.
Procedure for getting a new arrival stamp in the new passport:
Source: Immigration Division 1
Tel: +66 2141 9889