If someone is found wandering (or unconscious) with no id and no memory of who he is, what would happen to him?

I'm guessing he would be picked up by police and placed in a psychiatric facility of some sort. My question is, what would happen if he recovered and became capable of functioning in society and working and all but still had no memory of his identity? How could he get a drivers license and other necessary documents that would enable him to conduct busines and appy for jobs etc?