Lost Passport Experience?

Does anybody have some experience regarding losing your passport in Thailand?

I flew from Don Mueang Airport in Bangkok last night to Chiang Mai and dropped my passport either in the plane or on the walk between the Gate and plane at Don Mueang.

I flew on Air Asia and as soon as I deplaned I realized it was gone and asked the staff to check the plane and they couldn’t find it.

I leave Chiang Mai to another country in a few days and I’m originally from the USA. Does anybody have any similar experience? Air Asia doesn’t even have a lost item form and I’m worried.