Forgot Everything
My brother’s apple id has been forgotten so with everything he had put into security including password, email, and phone number used. How can he recover his account when he even forgot the security questions he wrote?
See if he can recover the ID/password.
Apple ID - How to find your Apple An iCloud e-mail address is an Apple ID.
Enter the Apple (iCloud) ID and click Forgot Password.
If he is being told there isn't enough information to reset them, contact Apple ID Support.
If he doesn't know the answers, if the steps in the article below don’t work, contact Apple ID Support, although based on multiple posts I have read, they will not help him recover the answers to his security questions.
Apple ID - If you forgot the answers to your Apple ID security questions.
From the article below.
Without proof of your identity via security questions and other carefully selected criteria, Apple Support can't help you reset a password or perform any other actions on your account. These policies are audited and reviewed on a regular basis.
Apple ID - Official Apple Support.
Contact Apple for help with Apple ID account security - Apple Support. (Link doesn't always load)
Get Support Work through the screens to get a chat option.
Apple Support schedule phone call
https://twitter.com/AppleSupport