If it doesn't show up at all under "Computer" go into "Disk Management" Right click Computer > Manage > DIsk Management. If it is missing in here then the card is bad. It it shows up here, initialize it if it asks to, otherwise right click the card and add new Simple Volume.
If you see it under "Computer" and when you try to traverse it and it asks to format disk. Format it. This happens when the MFT record on the SD card is corrupt and formatting it will fix it.
Answers & Comments
If it doesn't show up at all under "Computer" go into "Disk Management" Right click Computer > Manage > DIsk Management.
If it is missing in here then the card is bad. It it shows up here, initialize it if it asks to, otherwise right click the card and add new Simple Volume.
If you see it under "Computer" and when you try to traverse it and it asks to format disk. Format it. This happens when the MFT record on the SD card is corrupt and formatting it will fix it.