Will not start. Used it all summer and went to add Stabil and get it ready for winter storage and I cannot get it started. Fuel is on, has gas, replaced spark plug, checked air fillter, and used choke.

Do you have spark. Hold plug against block with a piece of wood and check for spark.

If no spark, start hunting down a safety or kill switch problem.

If it has a low oil level switch, check that.