iPhone disabled

See if he can recover the ID/password. Use every email address he can think of.

Apple ID - How to find your Apple    An iCloud e-mail address is an Apple ID.

Apple ID - Find              

If he forgot the Apple ID password, enter the Apple (iCloud) ID, and click Forgot Password. See if he can get a Rescue or Notification email option if necessary. Link to contact Apple Support at the end of the 2nd article.

Apple ID - Manage            

Apple ID – Forgot Password            

iCloud uses his Apple ID and password. If he has forgotten them, see the following:

If you forgot your Apple ID - Apple Support

or

If you forgot your Apple ID password - Apple Support