Apple ID isn’t working because it used an old corporate email. How do I access

I'd advise you change the email address except it requires acess to the non-working email acount.

If you find you can’t sign in, reset your password, or receive verification codes, you can request account recovery (go to this document: How to use account recovery when you can’t reset your Apple ID password - Apple Support ) to regain access to your account. Account recovery might take a few days or longer, depending on the specific account information you can provide to verify your identity.

Have tried logging in to old Apple ID but because it uses old defunct corporate email I can’t log in.

If you no longer work for that company, that company has already deleted your work email address. This is done as soon as you have left the company so that you can no longer log in. You no longer have any rights there.

An deleted email address, it is no longer valid, it simply no longer exists and it no longer works.

You may not be able to change that email work address because it is no longer exists.