1995 Chevy Caprice won't start

I have a 1995 Chevy caprice milage is about 103000 it's a 4.3 liter. Went outside one morning wa about to leave and went to start the car and it would not turn over whats so ever. We thought it was the battery when it came to jumping the car off that was not working. So we figured it was the starter went and got the starter checked and it failed twice so we bought a new starter from Auto Zone. Put that starter on and it was the same problem it would not start and when I say not start I mean it would not turn over or anything. We have tried to start the starter from underneath the car and still would do. We bought the ignition switch and put that on and still the same thing. We were told that it could be the resitor behind the ignition switch and if that was to be replace then they wwould have to reset the computer. We are not sure what the problem is. If anyone can help that would be great. Sorry I dont know much more of what's going on. Just going by what people have did to the car and what I have been told.