rest phone to factory iOS 7.1 now WIFI button is greyed out

My brother in law gave me his Iphone 4 when he got an Iphone 6, we reset the phone to factory with an operating system of iOS 7.12 and now the WIFI button is greyed out. I have tried turning it off and on, holding the button on the front and the on off, and tried resetting network and nothing is working. Any suggestions?