Pull the plug out and see if there is spark when the engine is turning over by pulling the rip-cord with the SP-Wire attached to the plug and the plug edge touching something metal on the engine. Hold it with a pair of pliers so you don't get a shock!
If it has spark, then it's either the cylinder is flooded with gas, or it's a fuel delivery problem or there is water in the fuel.
You can dry up the plug using a lighter and holding the end of the plug on the flame for 30 seconds - minute. For the cylinder, you can dry it up by draining all the gas in the tank, and then giving it about 10 pulls with the plug out of the engine. This will move air around inside the engine and dry it up.
Then put the plug back in, fill with fresh gas, re-prime the engine and give it a couple of pulls. (May take a few try's as the tank being empty of gas let air into the carb).