My camera says the card is locked

The SD card that your Canon SD600 is using has a miniature switch for the protection of the data from accidental erasure.

Hold the card against the light and you will see a tiny switch, about 1mm thick, in the small cut-out on one side. Now that your card is locked, sliding the switch to the opposite direction will unlock it.

im sure your not brain-dead and have tried to unlock the card. the problem is on the inside. i just fixed mine. you have to take it apart. and on the bottem of the card slot you will see a small metal tab. it gets in a bind and makes constent contact. thus showing the memory card is in the unlocked position. you have to cut that tab out. then put it together again.

well i would say take it to the store you got it from or look it up on youtube