I have mistakenly sent bitcoins to my old receiving address from Unocioin wallet and later i imported it into my wallet but it is not transferring it is asking private key. neither I' m able to send to any because it is asking me private key but i didn't know where it is? i have passphrase but how can i generate private key with passphrase?
Did you mean Unocoin.com?
As far as I can tell, Unocoin operates custodial wallets (via BitGo and Blockchain.info APIs), meaning that only they have access to the private keys. If this is true and you've transferred bitcoin into your Unocoin wallet, then the only way to retrieve it is to log into your Unocoin.com account (or contact their technical support for assistance).
You could also try sending a message to bitcointalk user dashingriddler who apparently is a Unocoin employee.
Check out this blog post. It's from the Blockchain.info website and details how to recover your wallet using the passphrase.