IPhone 4s wifi doesn't work?

When I go into my settings on my iPhone 4s, the wifi switch is grayed out and doesn't let me switch it on or off. There's no problem with my router. It's just the phone since it doesn't let me do anything to turn on or off the wifi. I tried resetting the network settings. I restarted my phone. I updated my software and everything. It is still grayed out. Any help is welcome!

Same here, but I was told to take it to the apple store but I haven't taken it yet.

Same here. Been a nightmare. Apple will only do something if within 12 months of receiving iphone. They send you back to network provider stating they have to repair or replace under EU law. But they're wrong as that law is for phone not working properly when received. If fault develops later they only offer to send for repair but you have to pay!