My iPhone 5C dropped and screen is black but sound still works

My iPhone 5C was charging until someone accidentally knocked it over and once it hit the ground, the screen was black. The light was still on in the background but it was black and then eventually the light went out too. I tried doing the resetting trick and even plugged it into the charger. The trick didn't work and when plugged in to the charger, it either plays the charging tone or charging vibration repeatedly. I tried plugging into my mac and it still recognizes my phone, but only tries to back it up (yet it fails to do that because it keeps telling me it cannot back up until phone is unlocked). I do admit, there has been some water damage to the phone in the past, but it had been working perfectly fine since then. At this point, I don't know what to do.