Brightness on my iphone isn't showing up?

I dropped my phone in water.got a new battery put in it and it worked fine.until i turned down the brightness and now my phone is completely dark/black and i can't see. Even when you shine it in light you can't see nothing. Its on and it still works. I just put my password in and it made the lock sound that let me in it and i'm getting all my notifications when i receive a message or a call but i can't read it. What should i do? What does it mean to format it? Its not unresponsive the brightness isn't on!

Try going to your setting--->brightness&wallpaper--->then you can turn the brightness down and up. Or you can double click your home button--->then scroll to the left--->and there's a brightness option there, but not for the iPhone 4.