How can I fix my DVD/CD rw drive?

Ooops, I think I uninstalled something important! Now I can't use my DVD/CD RW drive at all. The PC detects it (running on XP) when I uninstall and reboot but it 'falls over' while reinstalling the software with an error code no. 39. Without the drive I cannot reinstall the driver and allthough I have tried downloading from the net this didn't work. We thought the drive might have broken but a new one I have bought as a replacement is no different. Now, I have moved house and will not be able to get back on-line without installing new software via this drive. HELP ME PLEAAAAAAASE! PC is Dell Dimension 2400, replacement drive is SONY g120A.