Trouble with layers

Hullo everyone…
I have a problem here… you know how theres that tool with all the squares where you can put say, a cube in one square, and a camera in another. It works like layers so that you help organize your stuff… well apparently while I was modeling I might’ve pressed something and now it’s gone! any of you have an idea what to do to get it back? I really need that tool. Also, I don’t know if this has to do with the fact that, that tool is gone, but, when I insert a camera or lamp, it refuses to rotate, it just stays there in whatever default mode blender gives it. Any idea how I can fix it so I don’t have to do any weird acrobatics and make my life so difficult?

For the layers click the Numpad-/

For camera rotation unclick the Object-Center button just left of the layer buttons (the one with three cubes and a double arrow).