1. Don't panic. It is a relatively simple process that can be done with a few basic tools.
2. Shine a flashlight down the shaft to locate the socket.
3. Use a vacuum cleaner with a thin nozzle attachment to try and suck the socket out.
4. Attach a magnet to a piece of string or wire, and lower it down the shaft to try and retrieve the socket.
5. Remove spark plugs. Sometimes you can access it from the top after the spark plug has been removed.
6. Reach in with a bendable item. Sometimes you can reach in behind the block to retrieve what was dropped.
7. Fish it out with mechanic wire. Mechanics keep a long bent wire for fishing things out of tight spots.
8. You may need to use a borescope, which is a small camera on a flexible cable, to see the socket and fish it out.
9. Take your car to a mechanic. They have special tools that might make retrieval easier.
10. Try to reach for it with needle-nose pliers or some other long-handled tool.
11. Keep trying until you are able to retrieve the socket.
