hi, I recently had problems startin my lawn mower aswell, the problem was the flywheel had a layer of rust on it due to it bein in the shed over winter and was not creating a spark to the coil/plug, if you remove the cover off the top of the engine which also houses the pull cord mechanism, dont worry nothin will shoot out of place its comes off really easy(3 nuts) you will see the flywheel, clean around the edge with a wire brush and replace the cover, advisable to pull the pipe off the fuel tank and drain the old fuel out at the same time and replace with fresh fuel as petrol left standing de-composes and looses its strength, also take out the plug and clean or replace it. Hope this helps
chris
May 2008