Did you give Alaska a completely random US address, or did you give them the address of a friend? If you gave them the address of a friend, ask if they can mail something to you at the address you gave them to verify that address. Or just honestly explain the situation to another agent and see if they can help. There is certainly more they can do over the phone than in person. They may have a waiting period before you can use miles without flying activity (to prevent brokers from creating accounts and using them quickly). I doubt your miles are completely lost, but you may not be able to use them in time for a May trip.