remove the plug and lay it on a metal piece on the mower with the wire still attached and watch for spark when you crank mower ......if no spark you have a safety switch bad or a bad ingnition module
If you have spark ..take a dropper and put about a tablespoon of fuel into the cylinder and reinstall plug ...try to crank and if it trys to run its a fuel problem ....especially if you elt it set up for awhile with gas in the tank
bg, April 2007