Problem

I have some USB Flash Memory drives that I had used on a non-Windows system (ie a TV) so it is using another file system than Windows’ NTFS, FAT or FAT32. When I insert them into my Windows 10 laptop they are connected, ie they are found by Windows and show up under “Safely Remove Hardware and Eject Media” and in the Device Manager. But they are not assigned a drive letter and do not show up as a drive in the File Explorer (aka My Computer in earlier Windows versions) or command prompt.

At first, I just thought that the USB Memory stick was not working but after having the same problem with several USB Memories I realized it probably had something to do with the format on them. I tried to download the HP USB Disk Storage Format Tool, but the USB drive did not show up there either.

So how can I reformat the USB memory stick if it does not show up in the Windows File Explorer?

Solution

I found a solution that works for me from Mosely5165.

WARNING: Make sure you know what you’re doing before trying this. If you select the wrong disk you may loose your data or entire system.

1. Open a Windows Command Prompt as Administrator

cmd.exe

2. Run Diskpart

diskpart.exe

This should launch Diskpart and give you the DISKPART> prompt.

3. List available disks

list disk

4. From the list of disks select the one that is your USB drive, make sure to identify the right one.
WARNING: If you select the wrong disk you may loose your data or entire system

select disk x

5. Create a primary partition

create partition primary

If this gives you an error saying there is not enough space, give the Clean command, then try to create the partition again.

clean
create partition primary

6. Give the following commands.

select partition 1
active
format fs=ntfs quick 
assign
exit

Full thread can be found at Tom’s Hardware here.