Before my iPhone was good but after downloading a iOS7 I really suffering from a big problem of hanging and wifi

Before my iPhone was good. When I was using iOS6 some like this only. After that I got a message of update your iOS through Apple. I updated and than for 1 week it was ok after that my mobile start hanging. But now my wifi also start hanging most of times it doesn't work. It not ready to start. Not searching a available networks. Please help me. I want to restore a iOS7. Through update.