Figuring out if I blew a gasket or cracked cylinder head

To have an engine lock up due to a leaking cylinder head gasket, the leak would have to be really severe. That type of leak rarely comes on that quickly. It is more common that you would stop a warmed-up engine, then, due to the normal pressure in the cooling system, a cylinder would slowly fill with coolant. That would cause hydro-lock and a failure of the engine to crank to restart. If you think this is why the engine is locked up, remove the spark plugs, then try to crank the engine. If the head gasket is leaking, coolant will spray out of the spark plug hole when you crank the engine.