Hello Brittney,
In the above comment you mentioned that you have a manual focus option and the shot is out of focus... They adjusting the shot using the focusing ring manually (in manual focus mode). When the shot looks clear through the view finder, take the shot. Let us know if it is focused properly.
I am sure you must know how to determine if the shot is in focus... Incase if you don't: when adjusting manually, when the subject is in focus, while looking through the view finder a green light glows on the bottom left corner of the view finder, indicating that the subject is in focus... Take the shot, check if it is in focus...
If every thing works well, and the above shot is in focus, then the possible problems are with the lens (if it has an inbuilt focus motor). D40 lacks an inbuilt focus motor... So camera shouldn't be a problem. (or) problem with the camera and lens contacts... Remove the lens and clean the contact points on the lens and do the same on the camera as well.
--Adit