Unfortunately Gino Dan is right. Usually with anything that goes wrong with a B&D, Skil, or Craftsman tool you might as well throw it away. They don't stock parts for long and the cost of parts makes it debatable whether you should fix it anyway. Your options would be to look for a dead one with a good switch or to wire the drill direct around the switch and use it with a dead man's foot pedal. It's hardly worth it for just using the drill but the deadman's switch can also be used with drill presses, routers, and other tools. There is a slight decease in safety factory using a foot switch as opposed to a trigger switch, at least until you get used to using it.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.