Why does Blender render black? I have downloaded a .blend file that contained a pistol model.
Also, it contained a light.

The rendering was set to "Blender Game".

Since the default blender rendering doesn't require a light in the scene, and since I wanted to get rid of the light, I deleted it.

Since then the view shows a black weapon model:



I have set the rendering mode to "Blender Render", hoping that this would restore the default lighting, but it didn't help.

As one can see, the default blender scene also doesn't have a light, and it still renders fine:



How could I set the default blender rendering in this case?

Thank you very much for the help.
You should just click on the toolbar on the left > Create > Lamp: Point. In Blender Render, unlit objects show completely black. Make sure you move the lamp around (G) so that the pistol is illuminated by the light.

EDIT: It looks like you are in the Material view. Switch to Solid view (on the bottom toolbar)