If the software doesn't recognize your SD card, then there might be issues with the SD card controller. Go to Start > Run > devmgmt.msc and make sure there are no yellow items in the list. If the SD card controller appears to be uninstalled, then right click it and choose Update the Driver. At this point, you should let Windows Update do the rest.
There is also the possibility that your SD card is actually faulty. Use My Computer to access it. If you can't see it mounted, then it needs replacement.