Last time ours were "lost" they were in (adult) DD's coat pocket, she had left something in the car and fetched it during the evening (she doesn't drive). Irony was she was screaming at me that she would be late to an important seminar and she was wearing the coat!
Retrace steps, check shoes in case they fell inside, clothes, by phone, in fridge (yes found mine in there once!) kettle, anything you could have gone to straight from the door, oh and coat/bag lining, is it broken?