Playback button on my Nikon D3100 won't work?

It just doesn't work. I looked at my settings, and most of the playback options are gray and when I try and click on them, it says that those options aren't available with my current settings. I have no idea what settings that is referring to.

Since the playback button on a D3100 is a physical button on the back of the camera body, it's impossible for it to be "grayed out". What mode are you shooting in? Is there any chance your formatted memory card isn't loaded into the camera?