Lights Out After a Socket Sparked?

I was unscrewing a light bulb from a socket that has no switch. A plastic piece that connected to another fell off onto the floor. Figuring it was a safety precaution I went to connect it back. I presumably did something wrong and sparks flew knocking out lights on one side of our house. The electrical sockets still work, but the lights won't cut on. I tried flipping the breaker, but it did nothing. What do I do? Below is a picture of what the socket looked like after sparks flew. As you can see the accompanying plastic piece is missing from one side.