sounds like a short. i have encountered the same problem before. inspect the circuit along the bottom of the speedometer pod, if there was a short, either the internal fuse died, or that circuit is dead.
BenzWorld.org forum is one of the largest Mercedes-Benz owner websites offering the most comprehensive collection of Mercedes-Benz information anywhere in the world. The site includes MB Forums, News, Galleries, Publications, Classifieds, Events and much more!