I am new to the world of cryptocurrencies, so appologies if this is a noob question.

I setup the core clients for Bitcoin, Litecoin and zcash, but hadn't recieved any transactions.

Since then I've replaced my computer and don't have access to the wallets anymore, but I've also now been sent transactions to the public keys.

Because I know the public transaction keys, but I don't have the private keys, is it possible to regenerate the private keys?

If it is possible, how would I then add the public and private keys to a new wallet?

Alternatively I can get access to the previous harddrive, but it has been formatted. Is there a signature-based deep scanner available to detect wallet files?

Many thanks