A vehicles engine that has overheated takes from 30 to 45 minutes to cool down enough to be able to open the coolant reservoir.
If you've lost coolant and have some water you can add some water to the coolant reservoir to get the vehicle to an auto shop to have it fixed.
If you don't have any water or coolant to refill the reservoir or the engine is still overheating even though you have coolant then you should call a tow truck to have the vehicle towed to a shop so you don't damage the engine.