Blender render appears completely Gray When I hit "render" nothing appears except one object I forgot to add a material to. I'm unfamiliar with most of Blender's rendering settings. I've done some internet research but turned up largely nothing useful. I still have this problem. I've tried cycle's and the blender rendering engine. In fact this problem occurred when I switched from cycle's to blender...

For the record I am not willing to put my hard work up on here, but if you need information I can definitely post a screenshot of whatever it is that you need.

Some screenshots:
Go back into your material settings on the objects not being rendered and turn off Use Shader Nodes, if you are rendering in the Blender Internal render instead of Cycles.  This selection is next to the Material Text box just above the Surface / Wire /  Volume / Halo buttons and to the right. of the text box.