If you used encryption on a smartphone, camera or other portable device when storing files on a microSD card, data on the device may be inaccessible if you forget the encryption password. If you attempt to format the encrypted card without the password, the computer or device on which you attempt the process usually displays a security error that prevents the format. Consequently, if you want to format an encrypted microSD card, you must wipe it completely using a specialized disk utility in Windows.
Connect the card reader data cable to an empty USB port on the computer. Wait a few seconds for Windows to detect the device and install a driver for it automatically.
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Insert the microSD card into the adapter case. Insert the adapter case with the microSD card into the "SD," "MMC/SD" or "SDHC" port on the card reader. Wait for Windows to detect the microSD card and configure it as a removable storage device.
Press "Windows-I," then select "Control Panel." Click the "System and Security" icon, then click "Administrative Tools." Double-click "Computer Management" and select "Disk Management" in the new window.
Select the volume name of the microSD card -- it appears as a Removable Storage Device in the list. Record the disk number of the encrypted microSD card in the Volume list of the in the Computer Management window. The disk number for the microSD card is just to the left of the device's volume information in the lower pane of the Computer Management window.
Press "Windows-R" and type "cmd" in the Run box (without the quotes). Press the "Enter" key to open a new command prompt window." If a User Account Control warning message box opens, click "Yes."
Click inside the command prompt window, then type "diskpart" and press the "Enter" key. At the "DISKPART>" prompt, type "list disk" and press "Enter" to display volume information for all of the hard drives installed in the system.
Enter "select disk k" at the prompt where "k" is the disk number for the microSD card in the Computer Management window. If the volume number for the microSD card in the Computer Management window is "4," type "select disk 4" at the command prompt and press "Enter."
Type "clean all" and then press "Enter." Wait a few minutes for the DISKPART drive utility to wipe all data on the encrypted microSD card. Exit the DISKPART command window after wiping the microSD card with the utility.
Press "Alt-Tab," then click the Computer Management window thumbnail icon.
Click "Disk Management," then click the volume name of the microSD card you wiped with the DISKPART utility. Right-click the microSD card volume name, and then click "Initialize" on the pop-up menu.
Right-click the microSD card volume name again, then choose "New Simple Volume." Select "NTFS" or "FAT32" depending on the file format used by your portable device. Choose a drive letter for the microSD card in the drop-down list and click "Format." Wait a few seconds while Windows creates a new partition on the microSD card and formats it with the file system you selected. Click the "Finish" button to complete the process and exit the new volume wizard. Close the Computer Management window.
Things You'll Need
MicroSD-to-SD adapter case
If possible, back up any important data from the microSD card before using the DiskPart utility. Once you run the utility, retrieval of any data from the device is virtually impossible.