You absolutely need to pull out a spark plug, and then get someone to crank the engine for a second or two while you observe whether the plug is firing or not. EDIT: it will not fire by just holding it in the air -- you'll have to touch it briefly against the block, far far away from any place anywhere near gasoline or vapours. Or hook up a timing light instead of pulling the plug.

If it *is* firing, then your engine is flooded (petrol), and this can be solved by pulling the rest of the plugs and letting the fuel evaporate for an hour or two. There are other ways to unflood an engine as well.

Cheers