I reset iPhone 5S's settings and the Nike iPod app is just not there I tried to search it in spotlight and Siri but it's still missing
Nike+ iPod app disappeard
Did you try to re-enable it? To re-enable Nike + iPod on your iPhone 5S, go to Settings icon and scroll down to the Nike+Ipod app.
Toggle Nike + iPod to "ON". Once activated, you will see the Nike + iPod icon on your home screen again. I know, because I did the same thing on my 5S, and thought it was gone.