Can I get a blow up diagram for a Nikon DX AF-S 18-55mm lens

SOURCE: Nikon D50 autofocus

I just encountered the same problem. The advice giver who forced the focus ring with autofocus engaged was right on the mark. (Thanks!) Actually, I didn't need to force it, just gave it a firm push. Voila!

SOURCE: Nikon D80 Autofocus problem

Try re-setting the camera? On the D40 it is 'Menu' scroll down one to Custom Setting Menu (a pencil) and click reset 'ok' yes 'ok' this worked for me.

SOURCE: I have never been able to auto focus with my Nikon DX 18-70mm

Sure there's a cure! Auto focus on the 18-70 and a D70 has a few switches and menu settings that help to set it up. The switches are on the lens (I'm going to guess this is the one you're missing) and the side of the camera body. If you only have problems with this lens and other lenses auto focus fine, this is really the only thing that could make it not focus. The switch has two settings, M/A and M. It must be in M/A in order to auto focus. Older auto focus lenses don't have this switch.

The other switches and settings would result in auto focus not working with any lens you put on.

If you have problems with other lenses, or if the 18-70 is your only lens, drop a note here and I'll go into more detail on the other settings.

SOURCE: My d90 camera focus dosent work in af it keeps

Auto focus works by detecting differences in contrast. If you try to focus on something with no contrast, the camera will have trouble focussing. Try aiming the camera at something else the same distance away and keep the button pressed half-way while you re-compose the shot.

SOURCE: D40 with a Nikon AF-5 DX 55-200 lens will not auto

I had a similar problem with one that I bought. and come to find out, the gears internally in the lens where broken. I would return the lens, and get another one. Also when you go to buy a lens for your camera make sure that you bring the camera with you to test the zoom before you buy it.
Just FYI you also need to remember that with a smaller zoom your focus time will be slower, and it will take getting use to, unlike the larger zooms, you are trying to focus on a large area but being very detailed at the same time.