My DVD drive has disappeared....

My laptop has a Sony DVD+-RW DW-D56A. It recently started saying that it had 'found new hardware' and asking for drivers.

Everytime I rebooted it did the same and eventually I located a driver in windows\system32.

It has now stopped 'finding new hardware' and asking for a driver, but.....

AnyDVD says 'no DVD drive detected'
DVD43 says the same.
My Computer/Windows Explorer does not show it as being there

Device Manager shows it as being present (together with one called AVX which I don't have).

Where has it gone, why isn't it being detected.

Thanks in advance of any help