How do I recover Apple Account in old iPad without old email and password?

Without knowing the email address used to reset the password or the original purchase receipt to remove the Activation Lock, the device is no longer usable.

Your current account is not linked to that iPad at all. There is no identity verification when you open an Apple Account, so the only way you can prove the device is yours is with the purchase receipt or the email address you used to set up the device. Without either of those, anyone could steal your iPad and reset it for themselves.