Dear,
I am using sd card of 4 gb in my olympus camera, but today when I tried to use it, it is showing write protected.and I am not able to do anything with my camera.not even able to remove photoes even able to format it.
Did you check the tab on the card? It is fairly easy to bump the tab and enable write protection. Works like the old floppy discs, just push the tab back in and it should be fine.