Can't get my work to show on the cube I'm new to blender and am following a tutorial on youtube about making a nebula in a cube. I have done a lot of work and it's looking really good with my textures and such, so I save the project and go back in another time. Now when I open blender I can't see all my work show up on the cube anymore. I can still see all the texture files and such but the cube and background are just back to default. Is there something I am doing wrong? Is there something I have to press when I go back to blender to make it all show up again. I've started over 3 times now and the same thing keeps happening when I open my save.
Here are the 4 viewport shading modes: Wireframe / Solid / Material / Rendered. Use the shortcut Z to switch from a mode to another.

Wireframe to see the topology of your object, Solid to see the same but with a basic grey shade, these 2 first modes are ideal to work and move your objects, use AtlZ to enable transparency. Material to work on your materials, it won't take into account the lightings, so it won't give a good idea of your render. And at last, the Rendered mode, which is how you'll see your objects when rendered.