Changing a Drive's Read/Write Status

If you find that you cannot read or write or delete files on a drive, whether a memory stick, SD card or hard drive this can be fixed in two ways. The typical method is to right-click on the drive letter (e.g., C: or E:) and on the Security tab select Edit and uncheck any of the boxes that have Deny for permission.

If that fails because those options aren't available do the following:

1. Press the Windows key + R to open the Run box. Type diskpart and press Enter.

2. If you receive a User Account Control prompt asking for permission to continue, click Yes.

3. At the DISKPART> prompt, type list disk and press Enter.

Use the disk size to determine which one is your USB flash drive. In this example, we know that Disk 1 is our USB flash drive because its size is 14 GB.

4. Select your USB flash drive with the select disk command. In this example, we want to work with disk 1, so the command is select disk 1.

5. You can list the attributes of the disk with the command attributes disk.

6. To clear the read-only attribute (making the disk writable), use the command attributes disk clear readonly.

Or, to set the read-only attribute (making the flash disk write-protected), use the command attributes disk set readonly. 

7. When you are finished, type Exit to quit the program.

Source: ComputerHope.com