Why has a tiny irregularly shaped black speck the size of a broken pencil point appeared on my laptop monitor?

Is the dot persistent no matter what;s showing on your screen? If so, the pixels in that area are not performing as expected. This is commonly known as "dead pixel". There is no fix for it other than having your full laptop monitor exchanged. It is quite expensive so if you can still bear that dot for a while, i suggest you start saving since it is an early sign that your monitor lcd is failing. Expect to see the size grow larger in the next following months though. (depending on usage that is,)