I don't understand you. Do you mean Blockchain.info or the Blockchain of your Bitcoin-Qt? You can recover your private key / funds on Blockchain.info with your identifier, password or seed.
It is on blockchain.info. I stored it with a folder containing multiple documents in drive D. And after installing win it was lost.
How to recover my private key ? Plz help me
If it was a key which you exported out of blockchain wallet. Then just log-in back and you can export it out again, all you need is your identifier, password and your email address which you used to register to receive the 2fa email.