I got a new computer and had to reinstall ADE. I couldn't login to my old Adobe ID account and the password reset didn't work. Unfortunately, I created a new Adobe ID. I used the one email address I have for ages. It did let me create a new Adobe ID under my old email address with a new password. Now I cannot open my old epub eBooks anymore.
I found the old email where I created my old Adobe ID and it was the same email address I used today for the new account.