Why can't I use my iPhones Wi-Fi?

I have an iPhone 4 and for some reason I can't use it's Wi-Fi. I see it on the settings menu but it's not bolder to be clicked on and it just says " no Wi-Fi " this happens no matter where I'm( Wi-Fi area or not).It has been like this for a while, at one point my phone got wet but I had it fixed so maybe there's like a Wi-Fi chip that shorted out. But the solution could be as simple as clicking a button or getting an update. I just want to make sure. Can anyone help?

Maybe you have not set up your router inside your home for use at home, but when you go out, maybe you're not subscribed to a mobile data service, like giffgaff. Hope i helped x x x x