if you have a problem like my stepdad and me had with his memory card
for us it was probably our really cheap card reader about £5 for internal
there are 2 possible solutions
1. right-click on files/memory card and make sure that read-only is unchecked
2. after making sure the card is not hardware locked look at picture in post above, if that dosnt fix it follow on to step 3
3. you can put the card in a camera and reformat it and that will fix it, most cameras seem to ignore if the data has been flagged as read only (in software not hard ware