Guide: How to Fix Unallocated External Hard Drive without Losing Data?

Learn how to fix unallocated external hard drive without losing data via five feasible ways on this page. Besides, there’re related data loss prevention tips for you.


By Penny / Updated on April 2, 2024

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What is unallocated space and why is it important?

Unallocated space refers to any physical space on a hard drive that does not belong to a partition and no data can be written to it. So you cannot access this space via Windows File Explorer.


This area is important because it often includes significant amounts of deleted files.

Why is my external hard drive unallocated?

Are you wondering why is my external hard drive unallocated? There’re some common reasons for you.

  • Accidentally/intentionally deleted partitions
  • Accumulation of bad sectors
  • Corrupted or damaged file systems
  • Outdated or corrupted hard drive device driver
  • Windows recognition failure
  • Improper ejection
  • Poor connection
  • Power failure
  • Virus attacks

Before unallocated hard drive data recovery:

Are you wondering how to fix unallocated external hard drive without losing data? There're two points that deserve your attention.   

If you never deleted files from your unallocated external hard drive, you only need to recover deleted & missing partitions or fix unallocated hard drives.
If you've performed deleted actions or there's data loss, please recover deleted files & lost files from hard drives via the second part. 

Phase 1. Four ways to fix unallocated external hard drives 

Please refer to the following four methods to recover or fix your unallocated external hard drive. 

Fix 1. Recover lost partition on external hard drive via AOMEI Partition Recovery Wizard

Deletion is one of the most common reasons for unallocated space. Because the original space of deleted partitions will be designated as Unallocated in Disk Management.

At the moment, powerful AOMEI Partition Recovery Wizard is right for you to recover deleted and lost partitions via four steps. Moreover, if your new data hasn’t overwritten the data stored in your deleted/missing external hard drive, it’s possible to retrieve these files back after partition recovery.   

Other highlights of AOMEI Partition Assistant:
Recover deleted & missing NTFS, FAT, EX2, EX3, or Ex4 partitions.
Deal with fixing errors using CHKDSK.exe, disk formatting, merge partitions, partition creation, partition resize, etc.
Perform disk conversion between MBR and GPT, OS migration, etc.   
Support Windows 11, 10, 8.1, 8, 7, Vista, and XP (32/64-bit) computers.

Don’t hesitate to download its free demo version on your Windows PC now!

Download Demo Win 11/10/8.1/8/7/XP
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Step 1. After running this software, choose “Partition Recovery Wizard” on the left panel and select your connected external HDD. Then click the “Next” button.


Step 2. To find your deleted or lost partitions quickly, please choose “Fast Search” and click “Next” to go on.


Step 3. After scanning, you can see all the recoverable drives. Please select your desired external HDD and click the “Proceed” button.


After the partition recovery process, you’ll receive a Congratulations message. Please click “Finish” to exit this window.

Fix 2. Update/reinstall your external hard drive device driver

Obsolete or faulty device drivers can cause unallocated space because these drivers are essential to communicating between your storage device and the rest of your hardware. Problems can automatically emerge when drivers fail to perform properly. At this point, please refer to the following steps.

Step 1. Connect your external hard drive to the Windows PC. Then press “Win + X” and select the “Device Manager” option to open it.


Step 2. Locate “Disk Drives” and expand it.

Step 3. Right-click on your targeted external hard drive and select “Update driver” or “Uninstall device” as you prefer.



Step 4. Restart your Windows PC and the operating system will reinstall the hard drive automatically. You can also click “Browse my computers for drivers” and locate the unpacked latest driver.


Please remember to click “OK” to save these changes.

Fix 3. Create a new simple volume via Disk Management

If you desire to reuse unallocated space, you’re supposed to create a new simple volume from it or merge it into another partition next to it. Let’s begin with the former solution. This way also can help you recover lost partitions SD cards.  

Step 1. After connecting your external hard drive to the PC, press “Win + X” and select “Disk Management” to open this Windows utility.


Step 2. After entering the interface of Disk Management, right-click on the unallocated space and click the “New Simple Volume” button.


Step 3. Click “Next” on the Welcome to the New Simple Volume Wizard window.


Step 4. On the Specify Volume Size window, enter a smaller simple size volume in MB and click the “Next” button.


Step 5. Assign a new drive letter for the new drive and click the “Next” button.


Step 6. To erase everything on your external hard drive and make it ready for further use, select Format this volume with the following settings > perform a quick format > Next. Please ensure your selected file system is NTFS.


Fix 4. Extend volumes to add the unallocated space

Besides, you can also merge the free space into another partition via the following steps.

Step 1. After connecting your external hard drive to the PC, press “Win + X” and select “Disk Management” to open this Windows utility.


Step 2. Right-click on your external HDD and select the “Extend Volume” option.


Step 3. Choose the disk and specify the space you want to extend, then click Next > Finish.


Phase 2. How to recover data from unallocated external hard drives without losing data?

When it comes to recovering data from unallocated external hard drives, there’ll be no better way than using professional data recovery software because it’s the most efficient and safest way.

Deeply engaged in the data recovery field, MyRecover is ready for everyone to recover deleted & missing files from unallocated or healthy internal and external hard drives.

  • After data loss, please avoid writing new files to your external hard drive.
  • After external hard drive data recovery, please save retrieved data in a new path.
  • MyRecover enables you to recover 500MB of files for free. To recover a large number of deleted and lost files from your external hard drive, please consider upgrading MyRecover to the Professional or Technician edition.
Highlights of MyRecover:
  • Powerful features: Recover deleted & lost Word, Excel, PPT, folders, compressed files, photos, songs, videos, audio, websites, and other 200+ different types of data from internal & external hard drives, USB, SSD, etc.
  • Easy-to-find: Quick Scan and Deep Scan can find your deleted & missing files as many as possible. You can also quickly locate your desired files by Filename, Path, Date, Size, etc.
  • Convenient: Get deleted files’ original Paths, Filenames, and Format after recovery.
  • Excellent compatibility: Support NTFS, FAT32, exFAT, and ReFS file systems and be compatible with Windows 11, 10, 8, 7, or Windows Server.
Download Software Windows 11/10/8/7/Server
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Step 1. Connect the external hard drive to your Windows PC. After running MyRecover, hover the mouse over the connected external hard drive and click Scan to scan.


Step 2. Filter your needed data according to Name, Date, Document Type, or Path.

  • Name: Type the filenames of your desired files to narrow the search area.
  • Date modified: Set the date (today, yesterday, last 7/30 days, and so on) according to your situation.
  • Size: Filter the file size (<128KB, 128KB~1MB, 1MB~ 512MB, etc) based on your needs.


Step 3. Go to the Other Missing Files folder and select the data you want. Then click “Recover x files” to begin external hard drive data recovery.


Wrapping up

How to fix unallocated external hard drive without losing data? After reading this article, you may have a clearer understanding of unallocated space. And there’re five feasible ways for you.

If you want to prevent data loss at the source, please consider making regular backups via free backup software for Windows, AOMEI Backupper.

Penny · Editor
Penny works as an editor at AOMEI Technology, while she's a tester and editor for AOMEI Data Recovery Tools. She enjoys helping users with data recovery issues on Windows and iPhones using simple and practical solutions. Outside of work, she has a strong affection for pets, particularly giant pandas.