deck cuter switch is shutting down the rider why

My JD was running OK but now the switch that turns the cutting blades on shuts the lawn mower down looking for help please .
Also does anyone know does a belt run from the deck to the lawnmower itself or not .as it looks Luke I'm missing one .but not sure as I bought it used and only had it for two days .

deck cuter switch is shutting down the rider why