iMessage on Macbook Pro
I can't sign into my Apple ID it says "unknown error has occurred" and I've tried resetting everything - I can pull up a side window that shows the last time I was able to see messages but it never signs in - I keep getting "Type in password for this iCloud account if you want to continue using messages but the email that it shows is my original Apple ID that I no longer have access to and haven't used in probably 5-6 years.
MacBook Pro 15″, macOS 11.1