Depending on the condition of the tractor you may want to consider a kit like this.
http://www.smallenginewarehouse.com/...tegory=1710970
I'm not endorsing this company just putting it out for you to think about.
I'd do as Roland suggested and pull the spark plugs to see if it goes suck squeeze bang and blow rather that starting it. Hate to see you do more damage if it's fixable. How many hours on the tractor?