I need а private key I generated a BTC address in "Bitcoin Core" before 2 years ago, but my HDD is burnet and I lost everything. 

Unfortunately I don't saved file "wallet.dat" and I don't have "private key", but I have "passphrase". 
I install diferent versins on "Bitcoin Core", but I can only add BTC address and don't can make transaction.
I added my wallet address in "blockchain.com", but to make a transaction I need a "private key"
How can I get a "private key"?
You cannot. You need the wallet.dat file, unfortunately. Without a backup there is way to recover the funds.