First....check the very tiny slide switch located on the edge of the SD memory card. Make sure it is not in the locked position.
If that is OK:
If you can see the photos from the laptop, try to download all the images to your laptop hard disk.
After the photos are saved, delete all files and folders from the memory card.
Now put the card back in the camera and see if you can format the card with the camera.
I have a Casio Z750 that will not focus beyond macro (another story), while experimenting with settings and inserting cards back and forth between camera and laptop to view photos I have somehow locked 2 sd cards, screen reads "the card is locked". A sandisk ultra 2, 1gb & a sandisk 256mb. Can anyone please tell me if they can be unlocked.