If they are stuck pixels then there is still hope, you could use one of the many pixelfixer homebrews out there. If the pixels are dead however, then you're out of luck.
Dead pixels are white or black and are impossible to fix. Stuck pixels are the brightly colored ones like blue or red, these are fixable by flashing different colors really fast on the screen for a long period of time. Some say that putting light pressure on the screen while doing it may help as well.
I have fixed two DS consoles stuck pixels by doing this myself. The first time it only took a couple of minutes, the second time I had to have the DS on for hours until i fixed itself.