I had three stuck valves on my jeep. I poured my oil lube of choice into the spark plug hole. You don’t need a whole lot as you are not trying to fill the crankcase!
Next I bumped the starter with a screw driver in the hole ( I think I would recommend a brass drift next time). When I notice that the screwdriver wasn’t going up or down I would gently bump the starter and then gently tap the screw driver. If the screwdriver didn’t immediately begin to move I would bump the starter again.
I would do this until I could get the valve to go all the way down. Then bump again and see if it would go up and down. Couple of times at this and it worked fine. I think in my case it was tired old gas that gummed up the works.
Just be gentle and don’t beat the hell out of the valve. It worked for me but your mileage may vary!