Did it leak any oil on to the floor below it? In that amount of time oil will leak past the piston rings and fill the combustion chamber (assuming it was stored with the cylinder down). Check oil level first (it won't start if it's low on oil). Sometimes it takes multiple plug cleanings before it will start. Install a new spark plug - crank engine a few times - remove, clean and re-install plug - crank a few more times - remove, clean and re-install plug - crank a few more times - remove, clean and re-install plug - crank a few more times...................Get the picture? Clean plug with carb or brake cleaner. When engine does start (assuming there isn't another problem) it will smoke up the neighborhood for a while, that's the excess oil burning off. Then, for reliability's sake, install a new spark plug.