Try this 1
If the file system is RAW then the partition got damaged or corrupted.
Click on the below hyperlink "Formatter" and download the file
Try to format your SD Card using the utility provided by your SD-Card
Click on the below hyperlink "Guide" and download the file
Refer to the Page 5 (Platform Varies). You can find all the information.
According to your SD-Card manufacture, if you want to format it from a PC then
you are suppose to use formatter utility provided by them
Refer to Page 7 (Recommendation). You can find all the information.