Huawei Ascend G630-U251 Quick Start - Manual (Page 5)

Locking and unlocking the screen
Your phone automatically locks its screen after being idle for
a specified period of time.
Alternatively, you can press the power button to manually
lock the screen. You can go to
and touch Display >
Sleep to set the screen timeout period.
Follow the onscreen instructions and drag to unlock the
screen or open an application.