Try these things first.
Go to Settings>General>Restrictions and make sure that restrictions have not been enabled. If they have - turn them off.
Swipe to the right from the home screen and then type AppStore - in the search field at the top. If the app store appears - it is on the iPad, Tap on it and the App Store will launch. Leave the app and see if the icon appears.
Swipe from screen to screen to look for it.
Restart the iPad by holding down on the sleep button until the red slider appears and then slide to shut off. To power up hold the sleep button until the Apple logo appears and let go of the button.
Reset the iPad by holding down on the sleep and home buttons at the same time for about 10-15 seconds until the Apple Logo appears - ignore the red slider - let go of the buttons.
If all else fails you can reset the home screen layout - Settings>General>Reset>Reset Home Screen Layout. This will restore your App Store icon but it will also restore the home screen to the way that it was when you first set up the iPad.