Retrieving old email

I created an email account about 15 years ago that ends in sbcglobal.net. I still have the email and password saved but can't access the email because it says I need to login to AT&T with a user ID and password, but I don't believe I ever made one. When trying to use my old email and password to login to AT&T it says the account has been locked and I need to reset the password however it keeps saying my entries to verify the account are incorrect. Is there a way that I can recover my account?