1. Plug your device into your computer.[br]2. Turn off the device.[br]3. Hold the Power button for 3 seconds.[br]4. Hold the Home button without releasing the Power button for 10 seconds.[br]5. Release the Power Button but keep holding the Home button.[br]6. Keep holding the Home button until you are alerted by iTunes saying that it has detected a device in Recovery Mode
Make sure the device screen is blank and no logos are present. Same operation you can use for all other models of iPhone.