I presently have a Samsung

-likely the 'lock' tab on the memory card has been moved....a safety to prevent you from re-writing your card

Fix it by:
1 remove memory card from camera
2 look for the very little tab/switch on the front of the card
3 slide it to the unlocked position (opposite of now)
4 put it back into camera

if the tab/switch is missing do not dispair..
1 use a small piece of clear tape to cover this 'tab/switch' opening
-this is the same concept as cassette/vhs/ 5 1/4" floppies...removing the 'tab' to lock it