Q: I could not restore my iphone plz tell me about thiow cas hn I fix this problem

Hello, chsaadiqbal. 

Thank you for the question.  I would need more information regarding what exact error you are receiving to better assist you.  However, here are the best troubleshooting resources to start with when not being able to restore your iOS device. 

If you can't update or restore your iOS device

http://support.apple.com/kb/ht1808

Resolve iOS update and restore errors in iTunes

http://support.apple.com/kb/ts1275

Resolve specific iTunes update and restore errors

http://support.apple.com/kb/TS3694

Cheers,

Jason H.