Why does only the backlight turn on?

I have had this only for less than a month but this problem has been going on for a while now. I constantly have to keep my phone screen on because if the screen is turned off the screen will not turn back on until like 45 mins later. I constantly press the power button and constantly take the battery out and turn the phone back on but why doesnt the screen display work!? I can see the backlight only and this is so frustrating I want to cry.