If there is no spark at the plug, there is something wrong with the ignition system. Since it worked, then didn't, then worked again, and now won't, I'd check first for loose wires.
Troubleshooting electrical problems is much simpler if you verify blocks at a time so you don't keep going around in circles.
The distributor, as it turns, creates a pulse of electricity that goes through the coil. That builds up an electrical field that then collapses, generating a huge charge of electricity (30,000 volts or more). So, with the coil wire removed from the coil (or from the center tower of the distributor, have someone crank the engine.
Can you see and/or hear a spark/snap? If not, the plugs will never get a spark. So solve that problem first.
If there is no spark coming from the coil, it could be a bad coil, loose wires or bad ignitor. (Never assume anything is fine just because you replaced it.) Remove the wire from the negative side of the coil. Connect a wire to the negative side of the coil and touch and remove the opposing end from a ground (the engine should be grounded.) Does the coil spark now? Then it's good and the problem is the ignitor or the wire between the ignitor and the coil.
Here's a diagram that shows the connections:
diagram (scroll down)
Work your way through the whole system like that, and you will find the problem.
