We have a Polaroid I737 and the SD card is

On the left hand side of the card there should be a small tab (white most the time) You can slide this little tab up and down, In your case move it to side that does not say LOCKED or just the other side.

The lock on SD cards are for protection. Just in case you have pictures you don't want to get erased by accident,,,Just move tab to locked again!!!

Hope this information helped you out!!!