Help!!

My laptop suddenly shut down. I had to reinstall the operating system and then confirm it with my email — so far so good. But the email address that I’m asked to confirm is not the one I linked to the device. It’s a second-hand laptop, but it’s registered in my name. I understand this is part of Apple’s security system. Is there any way I can use my laptop again? I have the Passwort and everything for this laptop so it’s my laptop.