How to Fix Unallocated External Hard Disk Drive

Theo Lucia

Jun 16, 2026 • Filed to: Answer Hard Drive Problems • Proven solutions

Almost anyone uses external hard drives to save precious data or to extend the storage capacity of their Computer. But like an internal hard drive, they can become unallocated. Without allocation, you are unable to write, read, and store data on the unallocated disk. If you want to access your data on it, you might need to fix the unallocated hard drive and then recover files from the external disk.

Part 1: How to Backup and Recover Data from Unallocated Hard Drive

Dealing with an unallocated hard drive can be frustrating, but repairing it is not impossible. Before attempting any solutions, it is advisable to back up all data stored on the drive to prevent any potential data loss during the repair process.

1. Perform Hard Drive Data Recovery with Recoverit

The method below can bring back to life your unallocated external hard drive in most cases, depending on the cause of the issue. However, it also deletes everything on the hard drive and it cannot be recovered afterward.

Luckily, there is another method to recover your valuable data. The software is called Recoverit Data Recovery and it has brought immense improvements in data recovery solutions.

2. How to Recover Unallocated Hard Drive

Download and launch Recoverit Data Recovery on your computer, and follow the next steps to recover data from the unallocated external hard drive.

Step 1 Hard Drives and Locations. To recover data from external hard drives, you can click the Hard Drives and Locations section. Make sure your external hard drive has been connected to and can be detected by the computer.

Step 2 Select a location. Choose the connected external hard drive you wish to recover data from. Click on it to scan lost data.

Step 3 Scan the unallocated disk. Recoverit will first launch a quick scan on your unallocated hard drive. You can also go to the "All-Around Recovery" mode to deeply search more files from the hard drive, but it will take more time.

Step 4 Retrieve the lost data. After the scan has been completed, you will be able to preview your files. Select the wanted ones and click "Recover" to get the files back.

Part 2: How to Fix Unallocated Hard Drive?

Method 1. Using CMD to Repair Unallocated Hard Drives

Before searching for powerful tools that are specially designed for such occasions, you could try to fix the unallocated external hard drive by using CMD and more specifically "Diskpart". Here are the steps:

Note: This method will erase all data on the external hard drive but it can make it reusable. The good news is that you are still empowered to get the erased data back by using a hard drive data recovery program.

This method might or might not work, depending on what has caused the hard drive to be unallocated.

Method 2. Using Disk Management to Repair Unallocated Hard Drives

To repair the unallocated external hard drive, you can utilize Disk Management to create a new partition. Here's how:

Following these steps will enable you to successfully repair the unallocated external hard drive and use it for data storage once more.

If you are not sure if your hard disk is unallocated, you can move on to Part 3 to learn what an unallocated hard disk is and what causes a hard disk to be unallocated.

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Part 3: What Does Unallocated Mean

What is unallocated space on a hard drive

When trying to use an external hard drive, after being plugged into the computer, you notice that the drive doesn’t show up in "This PC" (Windows 8 and 10) or "My Computer" (Previous Windows versions). You do a bit of extended search to see what is going on. In Device Manager under "Disk drive," it says that the "Device is working properly". After that, you check in Disk Management and see that the Drive is healthy. However, it also says "Unallocated". This can happen to a single partition. If there is more than one, it can happen to the entire Drive.

Then, you might be curious about the impact of unallocated space on the hard drive to us when using the hard drive, external or internal.

Data can be only written, read, and stored in allocated space on a hard drive. Unallocated space, also referred to as free space, is an area where you can't access the stored data and write new data. So if you find the external hard drive unallocated, you should fix it and recover data from the external drive in the least possible time in case all important data present it to get gone forever.

Reasons for Unallocated Hard Drive

Many reasons can cause this unusual behavior and in many cases, not even an expert can figure out why it happened. Some of the known issues to cause a hard drive to become unallocated include:

2026 Technical Update: BitLocker "Read-Only" Policy

In recent Windows updates, a security feature may cause a drive to appear as "Unallocated" or "Read-Only" if it was previously encrypted with BitLocker and the encryption metadata is damaged. Before assuming the partition is gone, check your Registry Editor at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\StorageDevicePolicies. If you see a WriteProtect value set to 1, your system may be blocking the drive's allocation to protect data. Set this to 0 and restart to see if the partition remounts.

Distinguishing Hardware Failure from Software Locks

Not all unallocated space is a software error. If your hard drive makes a clicking sound, vibrates excessively, or if Method 1 (Diskpart) returns a "Virtual Disk Service error: The device is not ready," you are likely dealing with a physical hardware failure. In these cases, software solutions like formatting will fail. Stop all troubleshooting immediately and use Recoverit to attempt a raw sector scan before the drive becomes completely unresponsive.

Closing Words

Hard drives help us store our most valuable memories. Whenever they fail for various reasons, every picture, work data, and even music collection that have been gathered throughout the years is in danger to be lost forever. Luckily, Recoverit Data Recovery is the exact professional tool to help you recover data from the hard drive so that you can enjoy them forever.