To restore the App Store icon on an iPhone, access the Content Restrictions section in the Settings, slide the option next to App Store to On, or disable the restrictions altogether. If the App Store is not present on the device, restore the iPhone to its factory settings.
Before modifying the restriction settings, make sure you haven’t simply moved the App Store icon to another folder or location. If you can’t find the icon, access the Content Restrictions section by tapping Settings, tapping General, scrolling down and selecting Restrictions. Once the prompt appears, enter the four-digit security code. Find the App Store option in the list, which is listed as Installing Apps on iPhones that run on iOS 7 or newer versions, and move the slider toward the On setting. To remove the restrictions altogether, tap the Disable Restrictions button located at the top of the screen.
Parents and IT administrators typically impose the restrictions to prevent access to certain type of content, and there is no way to restore the App Store icon if you’re not familiar with the security code. In case that you accidentally removed the App Store after jailbreaking your iPhone, restore it by connecting the iPhone to your computer and using the Restore iPhone option in iTunes. Make sure to update the iTunes software before performing the hard reset.