ORIGINAL: Rodney
If the throttle valve is stuck it is probably because of congealed castor oil residue. The easiest way to fix that is heat. If you have a heat gun, play it on the throttle/carb area and get it very hotso hot you can not hold it with your bare hand. Work the throttle arm back and forth and it should quickly free up. Once free, put some fresh fuel or after run oil in it and work it a bit. WD40 is not a recommended solution. WD40 is a water dispersant, not a lubricant, and can have adverse effects if there is rust involved as it will loosen the rust and turn it into a nice scouring compound to wear out the innards on you engine.
Never, Never us WD 40 as a lubricant because as mentioned above it is not. Good advice given by Rodney.
I had several engines that sat for 3 years before getting back and I used heat. I took the carb off and removed the o-ring to prevent that from being damaged and then applied heat. Worked great and the engine started up first try. Good luck.