Sony DRU500a problem

Drive suddenly stopped reading any type of dvd. I’ve tried upgrading the firmware to 2.0g, downgrading it back to 1.0d and 1.0f and nothing works. Drive light comes on when i insert a dvd and stays on for a while, then goes off. Tried erasing a dvdrw and keeps telling me that the drive does not contain a eraseable disc…It was working fine a week ago and nothing has been changed on the system since then. I’ve changed the ide cables, tried it in another computer…nothing works cept for cds. Any ideas?