How can I unlock my SD card on my canon digital camera?

I downloaded pictures to my laptop last night, and when I went to take a picture today, the screen said "card locked". I can't figure out how to unlock it! Help please:)

look for a switch on the card, if its pointing to lock then well move the switch

otherwise try to format the card in the camera

go hard

there is a little tab on the side of the card
push it the other way