Samsung J1 SM-J120F - Manual (Page 27)

Basics
27
Icon Meaning
Flight mode activated
Error occurred or caution required
Battery power level
Lock screen
Pressing the Power key turns off the screen and locks it. Also, the screen turns off and
automatically locks if the device is not used for a specified period.
To unlock the screen, press the Power key or the Home key and swipe in any direction.
You can change the way that you lock the screen to prevent others from accessing your
personal information.
On the Apps screen, tap
Settings → Lock screen and security → Screen lock type, and then
select a screen lock method. The device requires an unlock code whenever unlocking it.
If the unlock code is forgotten, take the device to a Samsung Service Centre to reset it.