Question about Outlook Express

I can't recover my son hotmail.com account. He has no alternative email, no telephonenumber, and so on. The alternative emailadress does no longer work. He never bought anything with creditcard, nor did he send emails. How do I get my sons account unblocked again? 

I can't recover my son hotmail.com account. He has no alternative email, no telephonenumber, and so on. The alternative emailadress does no longer work. He never bought anything with creditcard, nor did he send emails. How do I get my sons account unblocked again?