Many people argue that one of the reasons that they remain with exchanges is that they don't have issues of private keys. So, they won't have the stress to save private keys for long time. For the case of exchanges, what they need do is to provide email or any KYC requirements to recover their accounts.
How come your own case is different, and how manage did CZ issue you a private key?
Your posts suggest that you don't have a clue of what you said and maybe you never created a wallet anytime.