First we will try to repair our SD card using the command prompt in Windows.
Open command prompt in windows by typing "cmd" if you are on windows 7, Got to
Start,Run and type "cmd"
run command prompt cmd as an administrator
In the command prompt window, type "Diskpart" press enter and click on "yes" on the Task window
Type "List Disk"
Type "Select disk #" and press enter. where # is the number of your SD card. if you want to be sure
of the SD card number, check the size listed right to each to confirm.
Type in "clean" on the next line and then hit enter. If your Diskpart encounter an error at this point then we have to format the memory card so for that follow the steps :
Type in cmd "create partition primary" and then hit enter. you should get a message
like this "Diskpart succeeded in creating the specified partition"
Type in "Active" then press enter. again type in select partition 1"
Now type " format fs=fat32. now wait while your disk is being formatted.
your drive should now be clean and new.