FaceTime not working nor can't find the app?

I've been trying to FaceTime my friend it keeps saying unavailable on my end. I have the iPhone 5s and he has the iphone5c he can't even found the FaceTime app nor is it not even in his setting we need help

It's disabled on his iPhone. If you go in the Settings app to General > Restrictions, you'll find a switch there that allows your friend to reenable the app.