How do I approve my iphone from Icloud?

I forgot my iphone passcode. So I restored my iphone from itunes and created my new passcode. However I still need my old iphone passcode to access end to end encrypted data such as website passwords on keychain. Since I forgot my iphone passcode it says I can either reset the encrypted data or aprove my iphone from another device signed into icloud? How do I do that. The only device I have signed into icloud is my pc. thanks