Shut machine off then go to restart and it wont fire

If thats all the info you have you need to take it to the dealer.
those have way to many possible problems.
1. bad spark plug seal, dirt fills up the entire spark plug hole especially sand.
2. they have fuel pump pressure issues due to poorly constructed fuel pressure regulators.
3. fuel pump itself
4. if intake or exhaust is modified it may overheat after it shuts off (engines get much hotter after they are shut down) will not start if too hot
5. one of the three ignition coil might be failing
6. CDI may have failed
7. Spark plug might be hot fowled.