How do you determine what is the problem with a 67 Buick v-6 ignition system if it has not run in over a year and it has no spark at the plugs but the coil has 12v in and 12v to the distributor?

assuming it's an older style distributor with points, make certain that the points are functioning properly. There should be a cam with 6 "lobes" that cause the points to open. If the points are not opening properly the coil will not function. If you haven't set points gap and/or points dwell, you might want to find an old-time mechanic or some other experienced auto tinkerer to show you how to do it. The condenser could also have failed by sitting too long, but I'd check the points first.