1997 Monte Carlo won't Start

I tried to start my car the other day, and nothing happened. The lights came on in the dash, but the car would not turn over. I checked the battery, the fuses, the starter/solenoid, and nothing worked. I pulled off the ignition switch and fumbled around with it for a while. Then my car started and ran for two days and then would not start. I turn the key and nothing happens. Would it be the tumbler not connecting or the ignition switch???

Thanks for any help.

I tried this WD-40 trick that I found in this forum yesterday. It worked, my car runs but it is running really rough. Any ideas why this is now????