Canon A400 When the camara is switched on on the screen card locked is displayed how do l unlock this

Remove the SD card and look for the little sliding switch on the left side of the card (it's very tiny). If this switch is shown in the "Lock" position, slide it to the other unlocked position. If this switch is already in the unlocked position, slide it to locked and then back to unlocked one time. Reinsert the card and try it out in the camera.