My iPhone 3G won't sync with iTunes it says iPhone can't befound?

My iPhone 3G won't sync with iTunes it says iPhone can't befound?

If this thing happens is that i think you have to restore so it can detect it in dfu mode. If you are willing to do it heres how.first turn off your phone.plug it in the usb port while you doing it
hold home until it comes to a screen that says connect to itunes. Then itunes will detect the phone. Then restore.