MY COMPUTER SCREEN DOESN't WORK?

My lenovo flex 3 was working fine until one day I tried turning it on in my bed and it turned on but the screen never did! They computer can and everything sounded like it normally does and even my keyboard light was on except my screen backlight never has. I tried disconnecting the internal battery and pressing the power button and it remained the same. I connected it to my tv and my tv acted like nothing was plugged up.