Hi and Welcome!
Unless you are still running Windows 98, drivers for optical drives including external ones are part of the operating system.
So, at first, I would try the unit with another computer. And don't forget the PSU This should rule out bad drive hardware.
Additionally, you might please check device manager (for some reason, my crystal ball suggests you are running a Microsoft operating system) if there are any problems reported. If so, try the (semi-)automated solutions by MS (http://fixitcenter.support.microsoft.com/Portal) first.
Please report back then.