How to fix the auto focus of a slr lense?

I had my DSLR camera in its case with the lens attached. I didn´t realize that it was open and when I grabbed it the camera fell down and the lens received most of the impact. When I turned it own to see if everything was ok, I found that the Auto Focus of the lens was not working. Is it possible to fix it? It is the kit 18-55mm lens that comes with the body, so I am not sure if it is worth it to fix it or just buy a new one.