after resetting iphone, keep asking me to enter old passcode to recover

Hello kamini147!

Have you followed the instructions found in this Support Article: If you see an iPhone or iPad unavailable message or Security Lockout screen - Apple Support?

If you need further assistance, feel free to reply back!

I hope this is helpful. Good Luck!

So, if I am understanding this correctly, you are trying to Restore your iPhone, iPad, or iPod touch from a backup - Apple Support. Is this correct?

In this case, the password you would be asked for is your Apple ID password, which you seem to have forgotten. So, please see If you forgot your Apple ID password - Apple Support, to learn how to reset it, and regain access to your account.