WiFi on my iPhone 4S not work

The wifi does not work. When I go into settings>wifi it just shows the loading symbol. I have restarted it, hard restarted it and reformatted it. It till donst work. I know the phone is the problem because I tried connnecting to two diffrent networks that other people could connect too. The firt day I noticed this, the wifi would sometimes come on and then off, then today it didnt go on at all. Any help??