My 512Mb Secure Digital card has started behaving odd. All was fine and then it stopped being able to access some files. I can't delete them and several other files appear to get deleted but then reappear although with a file size of zero. Now nothing on the card appears to work but I can still add files that will work. So is it possible to reformat a card? Any suggestions as to what is wrong and would a reformat sort it? If its defunct where is cheap for SD cards nowadays.