IPhone keeps saying its dead and won't charge?

Okay so my iPhone has been through hell and back, but still manages to work. But the other day it died so I plugged it in and now it won't turn back on. It just has that screen of the empty battery flashing. I had it plugged in for days straight, please help! (P.S water had been spilt around it a day before this but it still worked after that.)

You have answered your own question. Water has got in and ruined it. It takes some time for the full extent of the water damage to become apparent, but now you know.
You could try taking it to a repairer. A substantial part of their income comes from fixing soggy phones; you may be lucky and need only a new battery.

OMG I HATE my phone! Its a iPhone 5 and I have had it for a few years. And it has been in the charger for about a week, and when I power on my phone I get to the lock screen (so far normal) But after I put my code in it dies. And ill do it for about 20 times before I can quickly turn off the Wi-Fi. After the Wi-Fi is off it stays on for a bit longer. Then I deleted all my social apps, then turned my Wi-Fi back on. After it staed for a minute or so I WAS SO HAPPY! Then I put my Wi-Fi back on and downloaded snapchat. After I did that I loged in and my PONED DIED!