is it possible, that i have to create a layer and assign my object to it bevore saving?

no

The only thing I can suggest is pick one of the invisible objects, right click in the viewport and assign existing material and pick lambert1. In 2012 objects lose there material for some reason but generally when that happens and objects are there and just show up in wireframe and when you go to shaded they are green.

I without more data or seeing the scene files and looking at the history of the object I really can't say why they are going away on you.

sorry