Hello I have a 1976 Impala that won't turn over lights and all work I change the starter I change the ignition and I change the ignition switch still no nothing can anyone help me

Make sure battery has a full charge and battery cables/connections all good. At the starter motor two voltage circuits, one comes from the battery, hot all the time. The other circuit goes hot with key in the crank position and may be wired through neutral switch, depending on your transmission. Any testing at starter motor, make sure transmission is in park or neutral and parking brake is set. Make sure vehicle can't move. If you have to get under vehicle to get at the starter motor, there are safety issues when working under a vehicle. Safety is your responsibility. Never use a bumper jack to hold vehicle while you work under it. Use quality jack stands to support the vehicle, on pavement. Even then something unexpected could always happen. If I remember correctly, that impala is a big body vehicle.

Chase down coil wire wire by distributer cap wire could be corroded and not touching that's what happened to mine follow it all the way down to fuse box

Safty neutral switch. Car wont start with out this working properly