If your iPhone gets stuck at the Apple logo and won’t continue to reboot, it is possible to put the iPhone into recovery mode and restore it from a backup. To do this, connect the iPhone’s USB cable to your computer, but don’t plug it into the iPhone yet. Before you plug the USB cable into your iPhone, hold the Home and Sleep/Wake buttons until the screen goes dark and it shuts down.
Once your iPhone is completely shut down, plug the USB cable in and hold the Home button until you see the iTunes logo. When that appears on the screen of your iPhone, you will know that it has gone into recovery mode. At that point you can begin the restore process by clicking “Restore” in iTunes.