Does it read ok? Just CD's or just DVD's or both?
Does it show in Device Manager?
Are you able to insert a bootable disk and start from it?
Does the drive activity light appear to work?
Reads but doesn't burn? Probably a failed drive or software conflict. If its
failed, it's a candidate for replacement. Have you installed any third party
burning software?
In Device Manager, you'd want to confirm that there is no yellow bang in
front of it and that it is being recognized correctly.