To avoid starting problems next season, run the mower until it is cut for lack of fuel. This should remove most fuel from the carburetor and bowl and help prevent all gumming up. To prevent corrosion, allow the mower to cool, remove the spark plug and place a teaspoon of oil through the plug hole. Pull the starter cable a couple of times and replace the plug. Remove all the caked grass from the bottom of the shelf as it can ferment, acidify and eat through the metal over time.
Useful Links
Briggs and Stratton Oil recommendations
Locating engine model numbers, types and codes for outdoor power equipment in small Jack motors
If you can't start your lawnmower, maybe it's time to buy a new one. Consult my guide to choose and buy a lawn mower that analyzes the pros and cons of the electric, gas and battery models.
My personal experience with lawn mowers
I don't fix the turf equipment professionally, but I learned all this by playing with the engines since I was a teenager, and I have gained approximately thirty years of experience with lawn mowers, thread cutters and hedge trimmers.
