CD-RW

my SONY CD-RW CRX230ED has stopped reading any disc. The device manager says it is working properly. The latest drivers are already uploaded. But the drive keeps saying 'insert blank disc' even after a disc is in place. The green light comes on for a while once the tray closes and then switches off. No other action happens. I have tried the follwoign already, without success:-
1. Changed the master-slave relationship between CD-R and CD-RW, both on the drives and in BIOS.
2. Removed Upper and Lower Filters in registry.
3. Physically opened the drive and cleaned the lens and rails.
What to do now? I'd appreciate any help.
Thanks and regards S