Troubleshooting a Circuit Breaker Problem?

I have a wire that comes out of the junction box in the basement that works for 3 rooms on the second floor. When hooked up, the breaker blows. However when testing ceiling lights and outlets they show power going to them, but they won't work? After removing all the bulbs, now when the wire is hooked up, it shows power to everything and the breaker stays on, but nothing works. Could it be the breaker or something not grounded? This just happened suddenly in the middle of the night.