Why is my screen black but I can hear my notifications coming in?

So I dropped my phone outside a couple months ago it was cracked but it worked fine for a few months. Then I went to the store with my mom and left my sister and dad at home with my phone. When I came back I couldn't get into my phone at that time it still came on but it just had lines and stuff inside the screen. Now it's a couple months later and I tried to see if I could get into my phone now but the screen is just black. I can hear my notifications/alarms but I just can't see them... Can someone help me??