SD memory card damaged?

I was recording videos, then when I went to upload them to my computer it my camera (Nikon D5100) showed a message that said I couldn't use the card because it was damaged. I know that I have to format the memory card now to get it working but neither my pc and mac detected the memory card. So how can I format it if the computer doesn't detect there's a memory card?! Please help! The user's manual only says what I already know, not helpful lat all

1) NEVER format your card using a computer. Mac computers use a different format scheme and can damage your card
2) Always format your card using the format feature on the camera.

SD cards become damaged quite easily, one reason most high end dSLR cameras use CF cards.CF cards are very robust and in the 12 years I have been using them, I have never had a failure.CF cards also read and write data much faster than Class 10 SD cards

All you can do is use an other SD card and reshoot

This is an another reason to use smaller SD cards so when you do have one fail, you lose only a smaller number of image files, video or still

David is correct about SD cards. I'd say your card is done. Trash and replace.

Try the official SD Formatter, see if that can recognise it, but to be honest, if it's already experienced a problem, not sure how much you could trust it even if you did get it to work

No, no, no, no - a Mac will not damage a SD card. That is silly.

A Mac, if used in it's native file system, will format the SD card in a format that the camera can't read. So if you use a Mac, you have to make sure and format the card in the Fat32 or extFat format (not easily done in a Mac, as you have to issue a Unix command).

You can try running chkdsk on your PC, but if it will not recognize the SD card, it might not work.

You may have no option than to replace it.

Http://keerok-photography.blogspot.com/2011/05/memory-card-error.html
http://keerok-photography.blogspot.com/2011/05/how-to-keep-your-memory-card-healthy.html