Try restarting the tablet (turn it off and back on) sometimes that is all you need. Should that not work. Then try tapping (and holding) the background of the home screen which should bring up the info for adding app icons and widgets to the screen.
Should it still not work, then I would be looking at what app(s), malware or viruses could be on the device that is causing it not to work correctly. Those would have to be removed before it could be resolved.