First of all you have to give us a little more information as we are not standing next to you drinking a gin/tonic. Can you turn it in both directions only half way by hand? Did you check the oil level? Did the engine stop or just the blades? Can you give us the model and serial numbers from under the seat? Do you have any mechanical experience? From what you said I would guess that you broke a rod, but I’m a thousand miles away and at my age I cannot see that far.