Q: APPLE ID SIGN IN PROBLEM

I am using this old address since the beginning of Apple ID. Anyways, I want to manage my Apple ID. When I sign in and enter my Apple e-mail address (@apple.com). I was unable to sign in because Apple ID asked me to provide a different e-mail address which is my back up e-mail address. For some reasons I cannot access it. (only two email addresses I use) What is the solution?

My question is why cannot Apple ID verify my log-in? My login info is correct.

Need your help.