WIFI GREYED OUT PROBLEM

as in my iphone 4s wifi was greyed-out,no other alternatives worked rather than restoring my iphone .but the thing i wanted to know is that wont i b able to use the latest IOS in my iphone 4s?because the problem of wifi being greyshaded arose after i upgraded to ios 6.1.3.is my Wifi greyed out problem due to the latest software in 4s,as ios 6.1.3 may have been designed for iphone 5 only! cant my Iphone 4s never be able to update itself?????