Why is the phone screen Blank! HELP

Hi so i dropped my phone in the water and immediately dried it after that and and put it in rice now after some time my screen has gone black i cant see anything . But when i point a flash light at the screen i am able to see but hardly. Some people are saying that it is a back light damage now if i have to fix the back light would i replace the whole screen or just some thing within the phone and every thing else is working perfectly fine i do receive calls by sliding on the screen.

Hope i will get the answer