After the 6.0.1. update on my iPhone 4s the option for wifi has greyed out and cannot be selected. What can I do to restore wifi?

I have held off updated my iPhone 4s with the 6.0.1 but having problems connecting to wifi I thought maybe being out of date was the problem.

Having done the update the wifi option is now greyed out and cannot be selected at all. I have rebooted, forgotten networks and turned on and off so many times. There is nothing wrong with the wifi at home as other devices connect no problem. What can I do?