Did you watch the video yet and try using CFE cheat to 'dig' down and look around down through the hole. Often things sink below the surface. This makes them invisible on the surface because they are under the ground. I've retrieved all sorts of things this way. These things are not in the basement below. It's a different issue. You need to use the terrain tools to lower the ground level and look around down through the hole. If you find something all you need do it click on whatever it is and then hit the Esc key to make it pop up onto the surface.