That "restore" button in the Pages app is merely to restore the tutorial to the App and has nothing to do with restoring the app itself.
Do as lllaass is suggesting and search for the App. Chances are that it accidentally got moved into a folder or onto another screen on the iPad. Swipe from screen to screen to look for it. The spotlight search will confirm that the app is on your iPad - and you can launch the app from the search - but it will not tell you where the app is on the iPad.