I was driving and I had the belt tensioner pulley start to slide off. The bolt that holds the pulley on is now screwed up and I can't get a new nut on. How do I change the whole tensioner? Its the pulley that is to the left of the alternator or to the right of the crank pulley if you are looking at it from the passenger side.

 

Your best bet is to take your VIN number to a Hyundai dealer parts dept and see what they can come up for you.They have the entire set up on microfilm and can pull up exact pictures if needed.
You might be able to obtain an aftermarket part that will work, but no guarantees there.