Learn how to lock or unlock the touch screen and the keys in samsung galaxy S3. When you do not use the device for a specified period, your device turns off the touch screen and locks the touch screen and the keys automatically to prevent unintended operations. To lock the touch screen and the keys manually, press the Power key.

• To unlock them, turn on the screen by pressing the Power key or the Home key, and then flick your finger in any direction.
• You can use the motion unlock for unlocking the screen. In the application list, select Settings, Security, lock screen, Screen lock, Motion and then select OK.
• To unlock the screen with the motion unlock, tap and hold a point on the screen, and then tilt the device forwards.
• You can activate the screen lock feature to prevent others from using or accessing your personal data and information saved in your device.