If the App Store icon seems to be missing from your iPhone 5, restrictions may be enabled on the phone to blog access to it. Check the following…
1. Open Settings.
2. Touch General.
3. Select Restrictions.
4. Make sure App Store is set to On.
If all looks well under Restrictions, and the App Store icon is still missing, it may be on a different Home screen. Be sure to flip back and forth between the screens to check.
It is also possible that the icon is on a different home screen or in a folder. Look on other screens and within folders. If you still can’t find it, try resetting the home screen by selecting Settings > General > Reset > Reset Home Screen Layout. This should return your icons to default settings and restore the App Store icon.