Drive Letter Not Available-Why and How to Solve It?

October 30, 2019

Can’t assign drive letter in Disk Management because a certain drive letter is not available? Follow this article to solve it efficiently.

The issue: drive letter not available

Drive letters are alphabetical identifiers for all the drives on the computer, such as internal hard disks, optical drives, SD cards, and external USB drives. If a drive loses its drive letter, you can’t directly access files saved in it and all programs relying on the drive letter can’t run properly.

Usually Windows assigns drive letters for each drive it detects automatically. You may assign drive letters manually in Disk Management under specific circumstances. Here is a real case:

“I just upgraded from windows 7 pro to windows 10 pro and many of my drive letters were changed. I can't change them back using Disk Management because the letters I need are not available to select from. All of my applications point to a drive "D" and that letter is not available. Only letters available are: I, L, M, N, P, Q, R, S, T, & V.

This needs to be fixed. I can't spend lots of time reconfiguring my programs and shortcuts to point to a new drive letter.”

This user can’t assign drive letter in Disk Management because the letter D is not available. How comes the issue of drive letter not available?

Why would a certain drive letter become unavailable?

If you find a certain drive letter missing from the list of available drive letters in Disk Management, it could be caused by:

  • You have permanently assigned drive letter for an external hard drive, so the letter is reserved for the drive although it is removed.

  • The drive letter is occupied by a hidden removable device or DVD/CD-ROM.

Then, how to free up a drive letter currently in use?

How to fix the issue of drive letter not available?

To fix unavailable drive letters, you may need to make some modifications in Registry. Following are the detailed steps:

1. Press Windows Key + R to open the Run dialogue. Type regedit and press Enter or click “OK” to open the Registry Editor.

2. Expand the entries on the left-hand pane to navigate to the following path:


3. Right click on the device with the drive letter you want and select Rename. Change the letter to any other unused letter to free up the current one.

Registry Editor

4. Close Registry Editor and restart your computer.

The unavailable drive letter should be released after rebooting. The next thing to do is to assign the released letter to the drive as you want.

Assign drive letters in Windows with a powerful freeware

Since you already know how to assign driver letters in Disk Management, I’d like to introduce a powerful freeware to you, which can be used as an alternative. It is AOMEI Partition Assistant Standard.

As a specialized partition manager, it can not only help you change drive letters but also change partition type ID. It enables you to resize, move, merge and format partitions with just a few clicks. It supports all Windows PC operating systems like Windows 10/8.1/8/7/Vista/XP. Now follow the instructions below to assign drive letter for a particular drive via AOMEI Partition Assistant:

Step 1. Download, install and launch AOMEI Partition Assistant. Right click the drive to which you want to assign a drive letter, select “Advanced” and then “Change Drive Letter”.

Change Drive Letter

Step 2. Select the released drive letter in the pop-up window.

Select Drive Letter

Step 3. Click “Apply” to view pending operation and then “Proceed” to commit the operation.



When you encounter the issue of drive letter not available in Windows 10/8/7, you can fix it using Registry Editor. To assign drive letter for a particular drive, you can choose Disk Management or AOMEI Partition Assistant. However, AOMEI Partition Assistant offers you more useful features with flexible options.

For example, you can clone bootable USB drive to another USB drive and erase SSD before selling with the help of AOMEI Partition Assistant. Give it a try and you will be surprised by all the wonderful features it owns!