Old, new, whatever, doesn’t matter, Activation Lock is intended as a theft deterrent, it’s intentionally not easy to bypass it, and you need access to the associated Apple ID and password, or you need the original purchase paperwork showing the serial number and a discussion with the folks at Apple, or equivalent proof of ownership. Nobody here can help you with regaining access to that Apple ID, and Apple won’t help here without proof.
If you forgot your Apple ID password - Apple Support
If you forgot your Apple ID - Apple Support
How to use account recovery when you can’t reset your Apple ID password - Apple Support
Contact Apple for help with Apple ID account security - Apple Support