I have a Samsung Galaxy Note 4 and in the last few days, S Voice no longer speaks. I investigated into the application's settings and Enable Voice Feedback is greyed out. I have tried every everything I know to do to get it to work.The Note 4 is a very nice phone,but, it would be even nicer if everything would work properly.
I am sorry to hear of the issues you are having with your device. Did you notice if the S Voice disappeared after downloading a certain application or updating any software? Have you tried going into Settings>Applications>Application Manager>All>Tap on S Voice and clear data/cache and force close?