Its the passenger side seat, and doesn't move forward or backward. Is the whole seat broken? If not, where should I start on the repair?

 

Did you make sure its still plugged in? The connection under the seat could have become loose.

 

if it makes a sound like its trying to move, you might wanna check and make sure something isnt lodged in the tracks. on my passenger seat(manual) there was a penny in one of the tracks, so it wouldnt move anywhere.

It should be simple enough to remove, theres something about removing the seats in the 4th gen how-to's I remember seeing. Be prepared to do some work though.