Card Lock, when the card is not locked.

Look at your memory card. SD cards have a slide switch along one edge. The position farthest from the metal contacts locks the card, protecting it from writes. The position nearest the contacts unlocks the card.

Try placing it in you memory reader in your PC and see if you can get access to it.

If there is nothing on it you want to keep try to format it. This will erase any files you have on the card.

Then insert the card into you camera and format it there for the camera you are using. There is probally a lock protection set up for some pictures in the settings on the camera.

http://www.usa.canon.com/cusa/support/consumer/digital_cameras/powershot_a_series/powershot_a470#ServiceAndSupport

http://www.usa.canon.com/cusa/support/consumer/digital_cameras/powershot_a_series/powershot_a470#ServiceAndSupport

http://www.usa.canon.com/cusa/support/consumer/digital_cameras/powershot_a_series/powershot_a470#ServiceAndSupport

There is usually a switch on the side of most picture cards (I am guessing its an SD card) this is the lock switch. Try setting it to the 'Unlocked' position.
Good Luck!

There is a tiny slide switch on the SD card. It locks the card. Slide it to the unlocked position.

Look at your memory card. SD cards have a slide switch along one edge. The position farthest from the metal contacts locks the card, protecting it from writes. The position nearest the contacts unlocks the card.

Move the slide switch on the side of the card.

Is the slide switch on the side of the card in the locked position?

Remove the memory card from the camera. Note that there is a small slide switch on one of the long edges of the card. Slide the switch to unlock or lock the card.

take the card out of the camera and look at it closely. You'll see the LOCK switch.

Have you tried to pull out the card and see if there is a little slide lock on the card? if so try sliding the slide lock to the unlock position. if it's already unlocked, try accessing the card via your computer. You might need to format the card if it's new. I've run into this problem in the past with some new memory cards.

Another solution you might try is putting the card into the camera and see if there's a function in the setup menu that will format or unlock the card from within the camera. It's a longshot but worth looking into.