I did a small search, was unable to find any adapters that would let you interface the card with you pc. The only thing that looks promising is NuGaSa - WiiBrew, which dumps save from gc card to sd- but your card is corrupted so? Also I don't think that chkdsk will help at all as the gc card file system is not that of windows- it would not recognize the file system. If you could find an adapter it could be possible to somehow do a rawdump of the data and transfer it to an other card, but this is a big time wishful thinking. It may also be possible to access the data using one of the wii linux in some fashion, again- big stretch.
Best of luck.