why wont my iphone 4s connect to wifi anymore?

I updated ny phone with ios7 and I had no problems, I fhen updated to ios7.0.1 or something and I can't connect to any wifi. My 3g works but my pshone just won'tcnnect, sometimes it goes grey and I can't eveb turn it on. I have tried everything abd its not mu wifi router eifher. Help!!!!