Okay i have a 1968 Camaro unfortunately it stopped working and wont even crank anymore I've Changed the ignition switch tested the battery and the starter and they all seemed to be great and the lights work no idea whats wrong Help?

Neutral safety switch needs replacing/alignment, if an automatic?
Firewall connection making good contact from interior to engine compartment?

Welcome to team camaro !!.double check what you last did also!!