Stuck locks I've heard of and experienced myself, but the key not coming out is weird. This tells me the pins inside the lock are seized and not allowing the key to come out. I would spray a little chain lube into the lock and jiggle the key to get the pins lubricated and release the key. Spray more lube, then put the key in and out a few times, like a penis in a vagina, just to get everything lubed up.
Graphite lubricant is the best choice for seized locks, but in a pinch chain lube or even WD-40 will do the trick without hurting anything.