Not sure what engine, etc, but you need to have power to the coil (which is what the ign switch does when it's in the on position) and then the starter solenoid (which is what the ign swich does when it's in the starting position.) I suspect you have some wiring issues, maybe even a fuse. Check to see if you have power to other things such as lights, horn, wipers, fan, etc.. . At least that's a start..