How to assign a drive letter to an external usb 2.0 hard drive? [URGENT]

By msyed500 ·

Here is my scenario:

I have an external hard drive that was working fine until recently. It is being detected via USB in Windows XP, but it doesn't have a drive letter in "My Computer". So I right clicked on My Computer and clicked on 'Manage'.

Then a 'Computer Management' box pops up. Within this box, I clicked on Disk Management, and saw that this drive was recognized but isn't assigned a drive letter. The drive is UNALLOCATED and NOT INITIATED. I tried to initialize it, but it was not initializing it. The hard drive seems to be spinning and the normal light of the hard drive is on. The hard drive connects to the PC via a USB wire and uses the power from the PC.

The data on this external hard drive is very important, so I do not want to do anything that will erase or format the external hard drive. Can you please show me how i can access my files on this external hard drive; as I need to back them up to another working drive.

The external hard drive is:
ACOMDATA Photon 2.5 40GB Portable USB 2.0 Hard Drive - Silver (PHD040U2E-54)

I have Windows XP SP3 (supports USB 2.0)

Windows XP allows me to release the drive and detects it when I connect the USB wire to the PC, but there is no drive letter. How do i backup the data?

Please reply as soon as possible, as this is very urgent.

Also, will the steps in this article work for me:

Thanks and please reply very soon,

- Mansoor

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All Answers

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working fine.... so what changed?

by CG IT In reply to How to assign a drive let ...

Usually hard drives in external enclosures have a seperate power supply. Have you tried taking the hdd out of the enclosure and connecting it directly to the computer? See if that works?

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Don't Initialize It!

by devtrends.com In reply to How to assign a drive let ...

If you do not want to lose the data, certainly do not try to initialize the drive.

Like CG IT stated, you best option at this point is to disassemble the external hard drive case and attempt to connect directly to your computer. The problem you will run into is the fact that it is appears to be a 2.5" hard drive case (guessing from the model you gave). You will likely need some adapter to plug it into a workstation...

If the data is super important, take it to a data recovery place.

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Drive letter

by bigfern In reply to How to assign a drive let ...

Do you have anything else plugged into your machine, or maybe did you assign the drive letter to another network drive? Sometimes Windows will not pick the next available drive letter and want to assign the same letter to external drives (such as G:). If G: was assigned to a network drive then windows will not assign anything to the external drive.

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See if this will help

by Jacky Howe In reply to How to assign a drive let ...


Try rebooting the computer without any USB devices attached. Then plug in the USB drive, right click on My Computer, select manage, and then click ?Disk Management.? If the drive is not present in the Disk Management window or if you are not able to access it, then the drive may have failed. In this window you should see all of your connected physical drives, their format, if they are healthy, and the drive letter.

Change the drive letter of the drive. Right-click on the drive in the list, and from the resulting menu select "Change Drive Letters and Paths"

Click on Change so you can change the drive letter. Click Change. Select a new drive letter from the drop down list, preferably the one that is not normally used for this drive.

Click Yes on the confirmation screen and you are done.


Write down all fixed Disk and CD/DVD drive letters so as not to delete them. DO NOT delete any of the fixed hard disk drives or CD/DVD optical drives registry values.

1. Login with Administrative privileges.

2. Disconnect all USB or FireWire storage devices.

3. Open Registry Editor by typing regedt32 in the Run box and navigate to the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices. Right click on MountedDevices and select Export. Save this file as you may need it in case something goes wrong. Save it as Devices.reg, it should default to My Documents.

4. Under HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices there will be registry keys with the name that resembles the format of \DosDevice\X: where X can be any alphabet letter which corresponding to your physical system drive letter.

5. Delete all possible USB drives, FireWire drives and external drives which have a drive letter.

<b>DO NOT delete any of the fixed Hard Disk Drives or CD/DVD optical drives registry values.</b>

Exclude \DosDevice\A: which normally reserved for floppy disk drives.

The USB specification for a USB port is 500mA per port. If a device needs more then 500mA, the USB port may be switched off by the over current circuit.

To avoid too high a power consumption on the used USB port, connect the External USB device to a second USB port with the additional Power cable . This provides up to 1000mA to the USB device. If the device still fails, try a self-powered USB Hub, as they are, in most cases, able to provide more than 500mA per USB port.

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by msyed500 In reply to See if this will help


In Disk Management, I am not able to change the drive letter for this external drive. The only options given when right-clicking on it are:

- Initialize Disk
- Properties
- Help

Properties is stating that the device is working properly.

i did not take the cover off yet or mess with the registry.

If you guys recommend to take the cover off, how do I connect this to a desktop not using USB? I never did this in my life. Instructions will be very helpful.

Thanks all!

Please reply soon.

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Try the

by Jacky Howe In reply to Re:

Registry fix with the external drive removed. If that doesn't work try this.

You will need to dismantle the external drive and see if it is using a Sata or and IDE connector.
If it is Sata you will need a Sata cable and be able to connect a Sata power lead to it.

If it is IDE you will need a Notebook IDE Hard Drive Adaptor.

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may sound silly

by NexS In reply to Re:

But did you try plugging the USB HDD into a different computer to rule out that is a hardware issue?

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I agree

by TommyDeca In reply to may sound silly

Try the external drive on another computer first. If it still fails, open the box and take out the harddrive. Purchase an ide or sata adapter -> usb connection.

I've got these adaptors at work, and use them in situations when I need backup from a computer that won't boot.

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by msyed500 In reply to I agree

I tried this on a Vista laptop, and other XP desktops, but the problem still occurs.

I think I am going to open the enclosure. How will I know if it needs SATA or IDE adapter?

Where can I find those adapters online? Can someone please post links and I will go ahead and purchase them.

thanks for all the help.

I really hope the data can be retrieved so I can back it up, and I don't mind if the drive doesn't work afterwards (once I backup the data).

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by msyed500 In reply to Re:


I was on the phone with the manufacturer and found out that the drive is enclosed in a 2.5 IDE or PATA enclosure, and that is cannot be connected internally to a desktop due to its size. It would fit a laptop.

the errors i am having are showing that there is no partition, and i should simply use a data recovery program to grab the data, and then partition or format it to reuse the drive.

i will try this soon and i am hoping for the best as the data is valuable.

will update u all soon.


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