Change or Delete System Drive Letter via Registry to Remove Conflict USB or FireWire Drive Letter
In Windows operating system especially Windows XP, when plug in external USB or FireWire mass storage device such as USB key, flash drive, portable harddrive, the drive is not been assigned a drive letter by the system, hence the USB drive or FireWire drive is not showing in Explorer and no AutoPlay or AutoRun window pops up, although the device has been detected, in Safely Remove Hardware (show device but with no drive letter) wizard. The cause is probably due to ’stupid’ behavior of XP where it won’t find an available letter from free letters pool when the USB or FireWire external drive which has previously mounted and assigned a drive letter is been inserted to computer USB or FireWire port again, but that previously allocated drive letter has been taken up and used by another storage devices. Another possible reason is all 26 letters in alphabet has been used, but this situation is rare and unlikely.
There is a solution to USB or FireWire drive not showing in system error. However, the disconnect conflicted storage device to free up the drive letter fix may not practicable or usable by some, such as computer which are on a network or system running data transfer activity to all its drive assignments continuously flow without stopping, and thus disconnect or reassigning any mapped drives, networked drives, removable drives or other storage drives is not an option.
In this situation, there is another workaround hack to fix the no USB or FireWire drive issue. The workaround fix relies on the registry tweak below to change the drive letter that has been previously assigned to the mounted USB or FireWire portable mobile flash or hard disk drive. Or if users wish, can opt to delete any reference to the detected drives by the device so that when the storage device is plugged in again, the whole drive letter assignment will be start from fresh, and clean.
- Login to Windows as an Administrator.
- Open Registry Editor by typing regedit (or regedt32.exe in older Windows prior to XP) in Run command of Start Menu and then press Enter.
- Navigate to the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices
- Optional step which not required in Windows XP or later, right click on MountedDevices, then select Permissions. You can also click Permissions from the Security menu.
- Optional step which not required in Windows XP or later, check the option to make sure that Administrators have full control to the registry key. Change and revert back this setting when you are finished with the reset of the steps.
- If you run above 2 steps in OS earlier than Windows XP, quit regedt32.exe and run regedit.exe.
- Also in the HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices registry branch selected, in the right pane, find and locate a registry value which represents the troubled USB or FireWire drive. The registry key should have the name that resembles the format of \DosDevice\X: where X can be any alphabet letter which corresponding to your physical system drive letter.
Here’s a guidelines that you can follow to quickly determine which registry key is linked to your conflicted drive letter:
- Exclude \DosDevice\A: and \DosDevice\B: which normally reserved for floppy disk drives.
- Exclude \DosDevice\C: which normally is the system root drive.
- If you have more than one fixed hard disk drives, then any drive letters that are using by them is not possible linked again, UNLESS the additional hard disk drive is added AFTER you first use the USB or FireWire device that now unable to show.
- Same case with CD-ROM or DVD-ROM optical drive as above reasoning.
- If you have inserted and mounted a lot of thumbdrives, USB flask drive, or external hard disks before, you will likely still see a lot of remaining registry values that you won’t know which is which. In this case, double click on each remaining registry key values to view its binary data. Inside the binary data, there will be trace of the name of the device that this registry key represents. For example, figure below shows a Sandisk Cruzer micro USB flash drive.
With this information, search for a registry value that contains name of your USB or FireWire drive brand and model that having problem showing up in Explorer.
- Once the correct registry value is determined (for example, \DosDevices\F:), right click on the registry value name, and the select Rename.
- Change the drive letter (in the example is F) to another unused drive letter that hasn’t been used by another other drives, then press Enter.
- Now insert and plug in the USB or FireWire device into the port again (if it’s already inserted, take it out and re-insert again). The drive letter for the USB and FireWire should now appear and you can use the drive normally and properly again.
- For OS earlier than Windows XP which you have previously change the permissions for the registry key, quit Regedit.exe and start Regedt32.exe, and change the permissions back to the previous setting for Administrators (which should be Read Only).
It’s also possible to simply delete the devices registry keys instead of renaming it. Deletion is helpful is users really can’t find the the registry value for the drive letter that having problem. But make sure that you do a backup for the registry branch by exporting MountedDevices key, as mistake may cause your system unbootable. The delete all possible USB drives, FireWire drives and external drives which have drive letter temporarily only when inserted in the system, and DO NOT delete any of the fixed hard disk drives or CD/DVD optical drives registry values.
Share and contribute or get technical support and help at My Digital Life Forums.
Related Articles
- No Drive Letter for USB or Firewire Drive
- Change or Modify the Drive Letter and Paths in Windows Vista
- How To Mount and Access New Partition, Volume or Drive As Folder Path In Windows
- Change or Resize Partition (NTFS, FAT or FAT32) Size in Windows Vista
- Disable Auto-Run and Auto-Play of U3 Smart Drives Launchpad
- Prevent Viruses from Infecting the USB Flash Drive or Pen Drive
- How to Remove or Delete AutoPlay Handler from the Options List in XP and Vista
- Change and Set Different Input Method (Letter or Block Recognizer) as Windows Mobile Default After Soft Reset
- Vista: Reclaim and Release Disk Space from System Restore and Shadow Copies
- Unable to Open Hard or USB Flash Drive with Windows Script Host Cannot Find Script File autorun.vbs Error
Entries (RSS)
November 8th, 2007 15:54
[...] also possible to change drive letter to a free one via registry. Get help or contribute tips or tricks at My Digital Life [...]
November 9th, 2007 03:19
This article is trying to fix the issue in an over-complicated fashion and shouldn’t be followed… What’s wrong with simply carrying out the following steps:
Open the start menu and right-click on Computer. Select the ‘Manage’ option. This will bring up the Computer Management Console window.
Under Storage click on Disk Management. You should be able to find your USB / Firewire device listed but without a drive letter. Click on it.
Right-click on the item and select ‘Assign Drive Letter’. Select a free drive letter and okay OK.
Bingo - you have fixed the issue. This can also be used to change the drive letter assigned to a removable storage device.
November 9th, 2007 11:22
moggoly, your method is indeed very good. However, in most situation, the detected but no drive letter USB device won’t show up in Disk Management.
December 7th, 2007 19:28
moggoly you are the man your method is so simple. However i believe that there is the need for the alternative method too as admin pointed out.
December 16th, 2007 15:00
How about when the drive letter shows in the Disk Management list but does not show on My Computer or Windows Explorer
June 4th, 2008 14:12
Thanks! This registry edit guide was really helpful. I had some half-a-dozen letters taken up for the removable USB flash drives. By cleaning all the extra letters from the registry, I managed to get my USB flash drive operating once again.
June 9th, 2008 04:15
Sorry, it didn’t work for me. My external USB hard disk works fine in most PCs, I use it to backup my office laptop, but no way to see it in my home PC.
Detected, healthy, no drive letter, invisible in Computer/Disk Management, I deleted all registries but the fix devices (floppy, internal HDs and DVD drive): no news. Please help! Thanks.
June 25th, 2008 10:54
Interestingly, it also appears that all drives that can be somehow removed (Floppy, CD, USB, Firewire[, Zip]) begin with 5c 00 in there hex data. All of my fixed hard drives begin with 88, but I am not sure if this is just my configuration.
Also, it is also possible to conflict with network drives. At my workplace, no more than one flash drive could be plugged in and used, without unmounting network drives by logging off Novell, to remove Drive F’s mount point, then plugging in the drive (Logging back on to Novell would not create a network drive F when the flash drive was in)
Anyway, great article. This got things cleaned up after having many flash drives in my computer at the same time.
September 3rd, 2008 21:40
I upgraded my Dell notebook’s internal Fujitsu 60GB HD by cloning it to a new Western Digital 160GB HD temporarily installed in an external USB enclosure using WD’s Data Lifeguard Tools. When I then installed the new WD drive in my notebook, it worked fine. When the old Fujitsu drive was installed in the external hard drive case it showed up as a USB device but the partitions did not appear and were not assigned drive letters recognized on either my laptop or desktop PC’s. That’s when I Googled and found this site, but it did not solve my problem. THEN a light bulb went off and I realized I had password - encrypted the old hard drive within the Dell BIOS setup as a security measure, which indeed prevented the old HD from being accessed. I reinstalled the old drive in my notebook, disabled the password, put it back in the external case, and VIOLA!, the drive letters got assigned and data was all there, allowing me to now use my old drive as a backup external device. I thought this info might help add to this thread…