Start with having some twist the key and see if the rotor spins about. What about the points? Do they still open and close? Can you pull a spark plug out and hold against the block while some one cranks the thing to see the spark? Did you try a timing light on it?
The engine has probably a centrifigal advance with weights and springs and those weights swing out and retard the spark to make the engine run right at higher RPM. You should feel tension against the rotor when you twist it. If not, then perhaps the spring has broken or slipped off?
If you have a strobe see if the timing is going. If not hook a light bulb to 2 wires and put one on the points and the other on ground. As you rotate the engine with a breaker bar see if the light goes on and off which tell you that the ignition system has power and that the points are opening and closing.
Do you smell fuel in the carb?
If you've ruled out fuel and spark (ignoring all my 'sage' advice) then is the cam still turning and do you have compression?
