You need air, fuel, spark and compression.
Amazon or Ebay?
Bet that was first on the list LOL.
Is the mag right side up? Should be lettering on it saying block or front side.....
Take an old plug. Gap to 1/4" wide. Ground it out and check for nice blue spark.
Remove fuel line AT the carb. Drain into a glass jar. Should have a nice fuel flow.
Crack the gas cap and see if it mows grass again. If so the cap isn't venting.
Clean the cooling fins. Adjust the valves.
Shot in the dark. Check flywheel key. Make sure the flywheel hasn't turned on the crank.
Wouldn't hurt to decarbonize the engine.
Most likely you have a carb issue.