Odds are you have a short either in the wire or the head unit on the right side. Have you tried another speaker that worked fine on the left on the right side? If so and it did the same thing, track the wire back to look for a spot where the coating on the wire has been frayed and it is contacting metal causing it to ground out. If there is no sign of that in the wire, replace the head unit. If you don't feel like tracking the wire or it is a lot tougher than it looks, temporarily hook up a new wire and test it again. If it still does it, the amp on the right side has shorted and you have solved your problem. It is possible you frayed the wire yourself by accident and the consequent shorting could have caused the head to fry the amp on that side. It's not unheard of.