Does the lights on the dash light up when the ignition switch is in the run position?
No could indicate that the fuse link has burnt out. GM chassis fuse link is down by starter, Ford chassis the fuse link is near the starter solenoid on firewall area.
If the lights come on, it could be the neutral safety switch. Apply parking brake and try to start in neutral rather then park. Wiggle the shift lever while holding in start position.
Could also be connector on the ignition switch if GM. It is mounted at base of steering column