Screen wont lock!

[AC Question]

My Samsung Galaxy SIII (GT-I9300) wont lock when i press the powerbutton the screen just turns black and when i press it again it goes to where i was before i pressed the powerbutton even with a pin, pattern or password! and when i try to turn the phone off it just turns off the menu dosent turn up!??

Thanks for answers!

 

[Gelvira]

Try factory reset.