plug was wet so fuel isn't a problem.
it had spark to start, so most likely good spark. If you remove the plug, pop it into the plug boot and either lay it on top of the engine or hold it so that the electrode is grounded on the engine and kick it over, you'll see if it's got spark. Sometimes you may need to have someone help you look to see the spark....either way, sounds like you probably have spark.
air. If you're just in the garage or something, for sake of just getting the thing running, pull the air filter off....hopefully the airbox is clean!! See if it will start. Look to see how bad the air filter is and if the carb is very dirty. If the air filter is way dirty, and a clean one doesn't fix the problem, maybe look into the carb.
Also, you may want to check the pipe and silencer for obstructions. Take the silencer off and try to start it (don't run it for long without it on there....just to see if it's the problem).
Or, it could be bad gas.....
See if it starts with starter fluid being sprayed right into the carb. Oh yeah, and the choke should be on.
