Why is my screen not working properly?

About a month ago i dropped my phone and completely shattered the top left corner of the screen, branching out into more cracks. Since i've dropped it, over time, tiny pieces of the glass screen have been falling out and has now left about a one inch gap of the left corner of my phone, without the glass screen. A portion of the top left of the screen that you actually touch and use to operate the phone was also left exposed. About two days ago i dropped the phone again, falling on the corner that had no screen on it. I picked up the phone immediately and tried the phone on. As soon as i turned the phone on i was left with a black screen with a few red and green colored lines and whitish-grayish squares. When i got up this morning the screen underneath the glass part looked like it had been cracked and only a portion of the green and red lines remained and there are no more white-gray squares. I have no idea if i need to replace the screen or ive been told to open up the phone and replace something else. The phone hadn't been working properly before i dropped it the second times do maybe it isnt just the screen i have to replace..? I have no idea what to do, can anyone help me please?