1. Turn off your computer.
2. Get yourself a damp cloth, so that you don’t scratch your screen.
3. Apply pressure to the area where the dead pixel is. Do not put pressure anywhere else, as this may make more dead pixels.
4. While applying pressure, turn on your computer and screen.
5. Remove pressure and the dead pixel should be gone. This works
   as the liquid in the liquid crystal has not spread into each little
   pixel. This liquid is used with the backlight on your monitor, allowing
   different amounts of light through which give off different colours.

http://wiki.ehow.com/Fix-a-Dead-Pixel-on-an-LCD-Monitor