Iphone on black screen, looks like its turned off but it still vibrates?

My iphone4 screen randomly went black today. It was on 90% charge and then I dropped it. A few minutes later the screen went black as though it was turned off. I thought maybe it had run out of battery so I plugged it into charge, and my phone vibrated like it does when you plug it in, but the screen remained black. It still rings and the text sound happens but I can't answer or view anything because the screen is black. I don't have any money so don't suggest Apple please. My home button hasn't worked for months, so is there any other way to reset? If not, how do I fix my phone?

May be try to open the cover and reset it by removing the battery. Hope it works.search on youtube "how to replace iphone battery" they will show you how to.