Keyboard, power button light up but black screen

So a few weeks back my computer died on me and it was the motherboard, so I got the motherboard replaced but I was still having issues with my computer running so I go in get it reset yesterday. Everything is working fine, I used this morning to order a couple things from amazon. I come back from class and the screen is black but the keyboard and power button are still light up. So I shut it down and power it back on same thing keyboard and power button light up but the screen still stays black. Anybody have any ideas on why it’s doing this? And why when I used it this morning it worked but when I got back it didn’t?