I have a craftsman LT1000 lawn tractor with a Briggs and Stratton 18hp OHV Intek engine. It started for about 30 seconds then no spark at all. I replace the coil and sanded the armature (because it sat outside for over a year)off but not the flywheel. Still have no spark at all. I tried jumping all the safety switches and still nothing. Any help would be great.. thanks

You said you replaced the coil and sanded the amateur , they are the same thing.
Try and unplu the black wire coming to the coil and see what happens. If it starts check wirew for a bare spot, if it has a inline diode check that.
Luck