Aperture on my Nikon D90 camera disappears?

When I'm shooting my cameras aperture keeps disappearing so I can't take any photos. Is their any thing that I can do to make it not do this? Or do I just need to get it fixed?

What do you mean "the aperture" disappears? The readout in the viewfinder or on top of the camera?
Do you have it in a priority mode that won't display the aperture? Is there something broken with the lens? Try a different lens and see what happens.
If you do need to repair, NikonUSA services all NikonUSA purchases in the US… I've used them before and they are generally helpful and quite prompt and can repair most issues for a fraction less than a new camera would cost.
http://www.nikonusa.com/...epair.page
Hope this helps!