It says "card locked" when

What size is the memory card. If it's larger than 4GB then it won't work in the 5118.
Try using another card. Don't format it in your computer but do format it in the camera before trying to take pictures.

I know that you've also tried the tiny locking slide switch on the side of the card? But if so, the next thing to try is the lock switch in the camera itself. See the "toothpick fix" in this link.

Take the memory card out of your camera and look at it. SD and SDHC 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 to look at the side of the card it might be locked then unlock it

maybe your sd card is locked! try checking the lock button on the side of the card, and try taking pictures again, if this wont work, reformat your sd card.. but before doing it make sure to back up all your files!

SD and SDHC cards have a slide switch along one edge. The position farthest from the contacts locks the card, protecting it from writes. The position nearest the contacts unlocks the card. If the switch is already in the proper position, slide it fully the other way and then back again.
If that doesn't work, try another card.

Remove memory card from camera and slide lock in memory card (check photo).

SD cards have a slide switch along one edge. The position farthest from the contacts locks the card, protecting it from writes. The position nearest the contacts unlocks the card. If the switch is already in the proper position, slide it fully the other way and then back again.

SD card has a mechanial tab on the edge of the card to lock the card out to prevent accidental deletion of pictures by the camera . This tab had been accidently moved to the LOCKED position during CD card insertion/removal from the camera . Once tab had been returned to normal position . Every thing works fine now . JC

there will be a small projection at the side of the memory card. push it to its opposite side. this will unlock the card.
if not solve try that card in a card reader then use it in camera.