Nikon D5000 autofocus with a Tokina ATX lens?

I just bought a Tokina 10-17 Fisheye DX AT-X lens for my Nikon D5000, and it is not autofocusing.
I have searched the internet, but 'have not found a fix or a setting in the camera menu to get it to work. Any suggestions?

It won't autofocus on your camera because the D5000 doesn't have a focus motor in the body. You need to manually focus the lens.

Edit: see p.54 & p.60 of your manual.

The A TX lenses do not seem to have an in-camera auto-focus motor, so you will be using the lens as a manual focus lens, at least on any of the entry level Nikon dSLR's

This is NOT a big deal for a couple of reasons.

1) the apparent depth of field of a fisheye and extreme wide angle lens, especially at apertures of F8 and smaller is nearly from a few feet to infinity.
2) Nikon has a nice electronic rangefinder in the cameras view finder, so it is easy to assure perfect focus when manually adjusting the focusing ring on the lens

NOTE: I use a Nikkor 10.5 mm lens and manually focus it on my old D40 routinely. It is not a problem. Photographers have been manually focusing lenses for over a century. It is just one more skill for you to master