I need help to recover an alias hotmail account password when the security question cannot be answered and phone # is invalid

My cousin is elderly and has received an email from Microsoft that he needs a security code and must get it in 7 days.  He has an old Hotmail account and cannot remember the password for his alias Hotmail account ( I don't think he ever even accessed the alias Hotmail account in all these years).  When he logs onto his alias Hotmail account and cannot remember his password he can't remember the answer to his security question either (the name of his pet).  And the phone number on his account (a landline, not cell phone) is not correct because he has since moved into a retirement home.  He is panicked and thinks he will lose access to his old Hotmail account in 7 days.  How can I or you help him with this?  Thank you.