That's highly unusual. Maybe the app has somehow been disabled. Try this.
Re-enable pre-installed system apps
If you’ve disabled an app and would like to enable it, you can find and re-enable the app using the following steps:
- Go to Settings on your device.
- Swipe to view the list of All apps.
- Scroll to the bottom of the list to view disabled system apps.
- Touch the system app from the list that you’d like to enable.
- Select Enable.
Once a system app has been re-enabled, it can be viewed and opened from your main apps screen.