HT4623: Update your iPhone, iPad, or iPod touchLearn about Update your iPhone, iPad, or iPod touch
Currently Being ModeratedFeb 20, 2013 1:40 PM (in response to netty3012)
Try connecting in recovery mode: start iTunes, connect the USB end of the cable, then while holding the home button connect the dock connector end of the cable.
If that doesn't work go to this knowledge base article recovery technique.
Currently Being ModeratedFeb 20, 2013 1:41 PM (in response to netty3012)
Restore your iphone
If you are unable to restore then type "unable to restore" into the search bar at the top of this page by Support and read the resulting help article.It will tell you how to put it into recovery mode