Firstly, you'd do well to check that the drive is recognised by Apple System Profiler. If not, check the cables, and if it still doesn't show up, order a new drive - Remember that they have plummeted in price, so I wouldn't worry too much - You can get a much faster one than the one you have for the price of a few cans of compressed air! I'd use this as a good opportunity to upgrade.
David.