How to undo "remove all dismount" in Diskpart?

I made a boo boo! I executed the following commands in cmd:

diskpart
list volume
select volume 13
remove all dismount
exit

I have one of those dual-slot card readers with one slot for SD and one slot for CF cards.

The volume 13 was drive letter P for the SD cards. I also had drive letter N for the CF cards. I still have the N drive for CF cards and it works properly. But I have lost drive P for the SD cards. I tried unplugging the card reader and then plugging it back in. The result of it was that I could see both the P and N drive in Explorer, but only the N drive worked properly. Inserting an SD card in the reader and trying to open P drive resulted in some error message saying something like "there is no disk inserted".

diskpart did say that I needed to reboot after the remove all dismount command.

DiskPart successfully removed the drive letter, but your computer needs to be rebooted before the changes take effect. Diskpart successfully dismounted the volume.

So I rebooted but the problem remains. Now I only see the N drive. There is no P drive letter whatsoever in Explorer.

How do I correct this mistake? What's the opposite command of remove all dismount?

I just checked Device Manager. I can see the reader there, and the SD slot has been assigned drive letter O but there is an exclamation mark, and this drive letter is not appearing in Explorer.

Properties dialog states the following:

This device cannot start. (Code 10)

Click 'Check for solutions' to send data about this device to Microsoft and to see if there is a solution available.

If I click that it says it could not load driver software, and allows me to check online for a solution, which it doesn't find.

List mount point:

mountvol

alternative:

mountvol /L | findstr "\ ***"

Output:

\\?\Volume{093d583c-a043-11e1-b420-806e6f6e6963}\
    N:\
\\?\Volume{093d583d-a043-11e1-b420-806e6f6e6963}\
    C:\
\\?\Volume{093d583e-a043-11e1-b420-806e6f6e6963}\
    O:\
\\?\Volume{093d583f-a043-11e1-b420-806e6f6e6963}\
    R:\

\\?\Volume{31f40cd1-4088-11e2-b0f4-806e6f6e6963}\

        *** NO MOUNT POINTS ***
\\?\Volume{31f40cd2-4088-11e2-b0f4-806e6f6e6963}\
    I:\
\\?\Volume{093d5841-a043-11e1-b420-806e6f6e6963}\
    D:\

Mount logical disk P:

mountvol P:  \\?\Volume{31f40cd1-4088-11e2-b0f4-806e6f6e6963}\

Dismount logical disk P:

Warring! Delete logical disk letter!

mountvol P: /D

Run USB-device panel:

RunDll32.exe shell32.dll,Control_RunDLL hotplug.dll

Its very simple to undo"remove all dismount" in diskpart........

Path:

1. press Win+R ,then write "cmd"

2. write “ diskpart ” and then select “yes”.

3. write “ list volume ”

4. write “ select volume f ‘’(which you want to mount)

5. then write “assign letter=f”

6. exit

This solution might be easier for some users.

I found a Technet reference to this command. This is what it says about the parameters all and dismount.

all

Removes all current drive letters and mount points.

dismount

Dismounts the basic volume, when all drive letters and mount points have been removed from the volume, and takes the basic volume offline, making it unmountable. If other processes are using the volume, DiskPart closes any open files in use by an application before dismounting the volume. You can make the volume mountable again by assigning it a driver letter or by creating a mount point path to the volume. Dismount will fail if used on a volume that has any remaining drive letters or mount points. For scripting, using remove all dismount is recommended.

Note th part where it says you can make the volume mountable again by assigning it a driver letter or by creating a mount point path to the volume.

So go ahead and assign it a drive letter. Here follows a short how-to.

1. Click Start button.
2. Right click Computer.
3. Click Manage. This should bring up the Computer Management window. Click Continue if prompted by UAC.
4. Click on Disk Management.
5. Locate the disk with missing drive letter on the left side and right click on it.
6. Click Change Drive Letter and Paths.
7. Click the Add button and follow the instructions to assign a new drive letter.

Here are some screenshots.