lost memory from sd card

hi every one, IM new here, i used 2gb sd card to store my pictures, after i transfer all the pictures to my other pc i delete all the pictures from card, but now when i check the memory it shows only 990KB free space, but the card is 2GB memory card and there in no file stored, it is fully empty. I don’t know how i lost the memory, plz advise.
thanks in adv.