How do I activate my Apple Account?

Did you Deactivate your account using the steps provided here:

How to deactivate your Apple Account - Apple Support

If so, then the only way it can be reactivated is by entering the alphanumeric code that was given to you when the account was deactivated. Apple does not have a copy of this code and you would have had to save it yourself.

Here you go:

If your Apple Account is locked, not active, or disabled - Apple Support