My mower does not click or turnover when I turn the key?

My Ford YT 16 lawn tractor does not start. When I turn the key it is totally dead even after I charged the battery and even got a new battery. I know that when starting the mower I pull the full choke, put it in neutral, press the clucth all the way down and turn the key. I get nothing when I turn the key. Is their a kill switch that I am missing? Could the cutting deck be engaged? When the mower did start I engaged the blades and the engine stopped and then it was dead again. I have been starting the mower all summer. Help?