My spouse and I are in the process of fixing up our 1952 ranch home, and we've encountered an electrical problem (that we probably caused

We replaced the old exterior lights on both the front and back porch with new motion-sensor fixtures. We turned off the power at the correct breaker, and replaced the back porch fixture first. When we turned the power back on, it worked beautifully. So we flipped off the breaker again (they are connected to the same one) we proceeded with the front porch fixture. After it was finished, we once again turned on the breaker, only this time it did not work. Not only that, but ALL the light fixtures that are tied in to this breaker were not working (there are 4... front and back porch, plus hall and stairway light inside).

We thought perhaps we had wired the front porch fixture incorrectly, so we undid everything, flipped the breaker off and back on again, and still none of the lights will work.

If you haven't guessed, we are complete novices and don't know much about electrical work. But we did everything according to instructions, so we're a bit flummoxed. Any help you can provide is greatly appreciated.