Tango, a couple of things:
Recovery software does amazing things. We use it at work and it's surprising what it's able to pull off a supposedly dead card.
If you are not that worried about losing the pictures on the card try a format. Nine time out of ten that will bring the card back.
You say the camera says memory card 'locked'? If it's an SD card, just make sure the little locking tab on the side hasn't been switched on.