Some of your apps might look like the apps in one of these images:
Dim

White with lines

Don't delete the affected apps, or you will lose any of your content that's associated with them.
Restart your device, then go to the App Store and redownload the affected apps. To find Apple apps in the App Store, scroll down and tap "Apps Made by Apple." These are Apple apps:
- GarageBand1
- iMovie2
- iTunes U
- Keynote2
- Numbers2
- Pages2

- GarageBand is free on the App Store for qualifying devices that were initially activated on or after September 1, 2014.
- iMovie, Pages, Numbers, and Keynote are free on the App Store for qualifying devices with initial activation on or after September 1, 2013. Downloading apps requires an Apple ID.