Why I cannot wake up my LG Magna when it goes to sleep mode?

[AC Question]

I have LG Magna and whenever it locks or goes to sleep mode, knocking or double tapping the screen won't make it wake up. Even if I press the power button at the back, it just goes back to sleep. I did not have a problem when I bought it but when I had it screen protected it has been so difficult to use. Do you think it is my screen protector or just Android phones are naturally like this?

 

[B. Diddy]

Welcome to Android Central! This isn't normal behavior. Screen protectors certainly can reduce touch sensitivity--is it plastic or tempered glass?

When you wake the phone with the power button, how soon does the screen turn off again? Does it only turn off if you're not doing anything? Go to Settings>Display and make sure the screen timeout is set to a reasonable duration, like 30 seconds or a minute.