Hi chinns,
Thanks for visiting Apple Support Communities.
I recommend the troubleshooting steps in this article if you are not able to restore your iPhone due to an error:
Resolve iOS update and restore errors in iTunes
http://support.apple.com/kb/ts1275
If the issue persists, see this article for additional steps to try:
If you can't update or restore your iOS device
http://support.apple.com/kb/ht1808
Best,
Jeremy