Iphone 4 Restore Error 9

If this doesn't solve your problem, you may need to restore using DFU (Direct Firmware Upgrade) mode. To enter this mode, plug in your iPhone and turn it off. Hold down the "Home" and "Sleep/Wake" buttons for about twelve seconds. You'll briefly see the silver Apple logo and then your phone will appear to turn back off. Release the "Sleep/Wake" button but continue to hold the "Home" button until you see a message in iTunes stating that it has detected an iPhone in recovery mode. Choose "Restore" and you should be fixed right up!