Make sure it is empty first and foremost then follow until step three. If you get the top (receiver/barrel/toggle) off you can check sear bar rotation with all three intact. Push the front (left end with muzzle to left) end of the sear bar inwards, this should release the firing pin and bend the sear spring, when you release the sear bar should go back to its relaxed or prefiring position. Only if the firing pin is caught by the sear bar will the firing pin go forward when you press the bar inwards.
Luger Disassembly CLICK HERE