Eraserhead

My laptop has an "eraserhead" pointing device. Apparently sometime this evening one of my kids walked off with the eraser off of the eraserhead, rendering it unusable. Hopefully I can find it, or the spares that came with the machine. I know they were messing with the machine, because they presented me with the "]" key, which I can't figure out how to reattach. I tell you, they're like the gorillas with the Samsonite luggage, only computers aren't nearly as durable.