Why is it telling me my email is not valid?

I am trying to log into my Apple ID. I have retrieved my Apple ID. I have changed my password. I am trying to confirm my email with two-part authentication, where they send six digits to my email. After I enter the digits, the response I get is there is an error and it won't let me use my email. Not sure what to do. Has my account been hacked?

Thanks for your help.