Hey, I have a 91 Firebird V6 3

Hey, I have a 91 firebird v6 3.1L and I dont know what is wrong with it. It was running fine ever since I bought the car back in July, but a few days ago when I got in it and put the key in the ignition and tried to crank it nothing happens. The service engine light and brake light comes on and I can hear the fuel pump working fine but thats it, it does not try to turn over or anything. Here recently I have replaced the solenoid and starter and fuses figuring that was the solution, but still nothing happens. I have heard that it could be a number of problems with it like the igniton switch itself shortening out or its the neutral safety switch. I really just dont know what to do so if you could help me or at least shine some light on my problem it would be most appreaciated.