Can't download or update apps
My Iphone 5s won't let me update or download any apps. When I try to, it prompts me to sign in but then after doing so nothing happens, it doesn't even load (and yes i'm sure i'm typing it in my info correctly). Also when I try to enble automatic downlaods it won't let me either. It asks me to sign in but after doing so it asks me to sign in again and again non stop. I've tried restarting and signing in and out but nothing works. Please help.
iPhone 5s, iOS 7.1.2