My friend lost his PRIVATE Keys. Any way we can still retrieve the BTC Wallet? No other info can be provided only BTC Address.
No, private keys are randomly picked from the space of 256-bit numbers. A private key cannot be recovered from the address, otherwise anyone could take any other user's funds at will. If your friend doesn't have additional information such as e.g. a set of seed words, or a backup, it is infeasible to rediscover the private key.