The following troubleshooting steps have been effective in resolving this issue in most cases. If the following steps do not resolve this issue, I recommend contacting Apple Care (1-800-MYAPPLE {1-800-692-7753}):
1. Close All Apps on iOS Device: tap home button once > double tap home button > hold down on an app until all apps in this bar are jiggling with a red minus sign on them > tap the red minus sign for ALL apps (closing out of all apps currently in a suspended state)
http://support.apple.com/kb/ht5137
2. Sign out of iTunes & App Stores: Settings > iTunes & App Stores > Tap AppleID > Sign out
3. Reset All Settings: Settings > General > Reset > Reset All Settings
4. Sign back into iTunes and App Stores: Settings > iTunes & App Stores > Sign In with AppleID
Best of luck to all! Hopefully this is helpful, like I said if it is not, then I highly recoomend contacting Apple Care.