Further to Scrubby's post.
You need to work out if it is fuel or ignition
I like to use the red spark testers because you can see them in the daylight.
Also get a can of carb cleaner
First thing, check your oil level if it is low the engine could be seizing
Assuming that the oil is OK fit the tester ten go mow.
Watch the light, it should be glowing orange solid
When the engine stops crank the engine & watch the tester
No flashes = bad ignition
Regular flashes= ignition OK
Now grab the can of carb cleaner
Give the engina SHORT SHOT down the carb & then crank the engine
Engine fires = carb / fuel problem
If the engine does not fire do the same down the spark plug hole
Engine fires = valve problem
For this last one by fires, I mean a bang anywhere, through the muffler or through the carb
LEt us know what you find & we can take it further from there.