If you have a bad or missing ignition switch on your riding mower, there are two remedies for starting the engine. You either can install a new ignition or bypass the ignition switch entirely. The trick is to run a current straight from the mower's battery to the starter, taking the ignition out of the loop. This is a form of "jump starting" a riding mower without having to replace the ignition switch.
Approach your riding mower and check the gas tank to ensure there is adequate gas to power the mower.
Open the hood, and remove the positive and negative battery cables using pliers.
Put on rubber gloves and pour baking soda directly onto the battery posts, covering both the positive and negative posts. Let the baking soda set for a few minutes.
Open the jug of water and insert the wire coil brush to wet the bristles. Scrub the battery posts, removing the baking soda. This will remove all or most of the corrosion, allowing for uninterrupted current to flow from the battery.
Set the jug and wire coil brush aside, leaving your rubber gloves on. Attach the black booster cable to the negative post on the battery, then clamp the other end of the black cable to the mower deck or another metal component on the frame of the mower.
Attach the red booster cable to the positive battery post, then touch the free end of the red booster cable to the starter's positive side, which will have a "+" sign or be colored red. Your riding mower should "jump start" right away.
Immediately remove the red booster cable from the positive battery post and then disconnect both ends of the black booster cable. Close the hood on your mower and operate as normal.