Since i have IOS 6.0.1 i dont have wifi. HELP PLEASE

Since i am using the IOS 6.0.1 in my Iphone 4S, my wifi dessapeared. Im quite desesperate, i need my wifi, and an iphone whithout wifi, is just a PLASTIC THIN

I love my iphone, but this is keepping too long and a need any solutions please.

I