Ford Ranger 99 4.0 emergency?

Changed key switch because it was broken. Now purchased a new one put it in place now seems like there isn't any fire getting to the motor? Nothing will come on except interior lights radio. Headlights will come on bright battery seems good. But when turn over now there's a click but no fire?

Your motor has to crank to get any fire to the sparkplugs. Obviously if you are not able to crank the engine, you are not getting any fire. You need to give some more useful information instead of useless info. If the lights do not almost go out when you try to start the car, either the solenoid or starter is bad.

Just a shot in the dark, but Does your Ranger have PATS? If you changed the ignition lock, there could be an issue with the transponder receiver.