micro sd card protected

Hi,
Not sure if this has been covered or not,I bought an micro sd card over 2 months ago, i downloaded games on to it no problem, my son has been playing with them fine,
I have come to add more games onto it, and it will not let me, it brings up a box saying the card in protected, i have done nothing different, why is suddenly protected and how do i unprotect itThanks in advance
Rebecca

generally there's a tiny little switch on one side of the card. This switch can get moved when you insert the card into a reader, write protecting it. You need to move the switch back and carefully reinsert it into the reader.