IPhone 4S Wi-Fi stopped working after upgrade

Hi you all,
I was having an iPhone 4S and I haven't upgraded the iOS from 6 to 7 till now.
But As these days, it's become more popular, I would like to use those features and hence upgraded from iOS6 to iOS7.After that everything works fine except Wi-Fi. I have tried to restart and see but no luck. Apple diagnostic tool showing that my phone is charging problem, but I am not having any issue with charging / battery.
Anybody faced the similar issue? Please help me out here guys.
