Are you getting ready to cut your grass in the spring or is this something that happened during the mowing season?
If it is springtime, then more than likely the gasoline in the engine is causing it to not start. A thorough carburetor cleaning normally does the trick. In severe cases, replacing the carburetor is necessary because it just cannot be cleaned well enough. This would be the case of a lawn mower that has sat for several seasons.
On the other hand if you were mowing last week and you tried to start your lawn mower today and it didn’t start, there could be an assortment of reasons why it won’t. You could be out of gas. There may be no spark. Your flywheel key could be sheared. Something could be plugging up the fuel line. The spark plug could be bad. Your air filter could be clogged. Mice could have chewed up the ignition wiring and a bunch of other things could be happening.
With this scenario, you need to have a small engine mechanic check it out and troubleshoot the problem. You can find a lawn mower repair shop in your area by visiting our Locations page.