[Nyx]

Could someone please help me to find another phone number his might have, Or one of his relative's?
I must reach him, And I will call and call until he answers. I doubt the police will help in such a case.

The police will help unless you did something illegal to get the headphone amp, in which case you're boned. And I highly doubt anyone is going to help you, you'd be better off looking somewhere else.