"Restarting or entering recovery mode on an iPhone is quite easy. All you have to do is press and hold on to the sleep/wake button and the volume down button for about 10 seconds. Your iPhone is automatically forcing restart after this. To enter recovery, the steps are quite similar to force restart on an iPhone.
First, you will press and hold the sleep/wake button and the volume down button. Next, you connect your iPhone to a Mac or PC using the USB cable. Once you see the iTunes message on the phone, you release the buttons.
To go out of recovery mode, the steps are easy as well. Press and hold the sleep/wake button and the volume down button. Once the iTunes message disappears, you can release the buttons, and the phone should restart. "
To restart the iPhone, press and hold the sleep/wake button while pressing the volume down button for ten seconds. Due to the home button change, it's been substituted by the volume down button for the duration. The side effect of this technique is that the volume HUD comes up on the screen each time you force restart on the iPhone. Recovery mode is another feature, which can be derived by: Connect your iPhone to your Mac or PC with a USB cable.
Next, click and hold the sleep/wake button and the volume down button, even after seeing the Apple logo come up. Release the sleep/wake and volume down button once you see the iTunes message appear on the phone’s screen, “launch iTunes,” and you’ll see a message indicating that “there is a problem with iPhone that requires it to be updated or restored.”