Rendering and materials are black This questions has already been asked a million times, but nothing solved my issue so far.

Situation


I'm using Blender 2.72b. 
I'm not using nodes, just the plain old vanilla settings. But apparently I messed them up somehow.
I'm using the Mirror modifier.
I'm completely new to blender (and 3D modelling in general) and use it for a couple of days now.
I deleted the cube and made this model from scratch (no import).


In texture view everything looks fine:


In material view (and after rendering) everything is black:


Attempts to solve


I have a light source.
I have a camera.
I have no ceiling.
I have a material.
I have a texture.
Shadows are activated.
I tried using nodes and my output was well connected - no change, still black, so I stopped using nodes again (I had no idea what I was doing anyway).
I checked out many solutions posted on the web.


As my last attempt, I opened the vanilla start-up file again. Everything works fine with the cube. So I compared the material und texture settings step by step. It all seems the same. This topic is so extraordinary complex and I'm so bloody inexperienced that I'm stuck at this point.
You are in local view, which isolates the selected object, so you have no lights illuminating the object.  You can change this by pressing  /  on the numpad or by pressing the space bar and entering "Local View".