How to Fix Unallocated External Hard Disk Drive [5 Ways]

What does "unallocated" mean on an external hard drive?

When an external hard drive shows as "unallocated", it means that the space on the drive is not assigned to any partition, so the operating system can’t use it to store or access data. This usually happens when the drive is new and hasn’t been formatted, or if a partition has been deleted, corrupted, or lost due to issues like improper ejection, virus attacks, or file system errors.

An unallocated drive won’t appear in File Explorer but can be seen in Disk Management as a black bar labeled "Unallocated".Since the system can’t recognize it as usable storage, you’ll need to create a new partition and format it to make it functional again. However, if you lost data due to the partition becoming unallocated, avoid writing anything new to the drive and use data recovery software to restore lost files before reformatting.

In short, the user will not be able to use "unallocated" space until it's properly partitioned and formatted.

How to fix unallocated external hard disk drive on Windows

When you plug in your external hard drive and Windows shows it as "unallocated", it usually means the partition is missing, corrupted, or not formatted. Don't worry—your data may still be recoverable, and the drive can often be fixed with the right steps.

Let’s go through several effective ways to fix an unallocated external hard disk.

Way 1. Update the hard driver via Device Manager

First of all, outdated or corrupted drivers can cause your external hard drive to show up as unallocated. To fix this, you can:

Step 1. Press Windows + X and choose Device Manager.

Step 2. Expand the Disk Drives section.

Step 3. Right-click on your Local D drive and select Update Driver.

Step 4. Choose Search automatically for updated driver software.

Step 5. Follow the on-screen instructions to install the latest drivers.

Way 2. Check and fix hard disk error or file system error

Secondly, disk errors or corrupted file systems might prevent your external drive from functioning correctly.

1. Run CHKDSK to check and fix unallocated external drive

First of all, press Win+R at the same time to open Run, input “cmd” and hit Enter (be sure to run it as an administrator). Then type "chkdsk g: /f /r /x".

2. Check and fix the hard drive error via AOMEI Partition Assistant

When dealing with tricky commands or concerned about making mistakes, especially if your PC won’t even start, consider using a reliable third-party solution. AOMEI Partition Assistant is a top pick for this. Compatible with Windows 11, 10, 8, and 7, it offers a clean, intuitive interface that makes it simple for beginners and tech-savvy users alike. To scan and repair hard drive issues using AOMEI Partition Assistant, follow these steps:

Step 1. Download AOMEI software and open it. In the main interface, right-click the target drive and then click "Check Partition".

Step 2. Choose the "Check partition and fix errors in this partition by using chkdsk.exe" option, then click "OK".

Step 3. Wait for a while and click "OK" when it's finished.

Way 3. Recover the unallocated space via partition recovery software

In some cases, your external hard drive becomes unallocated because of partition loss. In such cases, you can use a trusted partition recovery tool, such as AOMEI Partition Assistant’s Partition Recovery feature, to recover the lost partition with just a few easy steps. As long as no new data has been written to that space, the original files can also be restored successfully.

Step 1. Go to Recover > Partition Recovery on the main interface. When you get into the partition recovery wizard, select a disk that you want to recover. Click Next.

Step 2. Select Fast Search. It is recommended that you select this option the first time as it is faster than Full Search. If you are unable to recover the lost partition using Fast Search then I recommend you try the Full Search option.

Step 3. Select the lost partition and click Proceed.

Step 4. Click Finish to exit this window after you see the congratulations message.

Way 4. Repair unallocated disk space by creating a new partition

If the previous methods fail to fix the unallocated hard drive issue, you can create a new partition on the unallocated space. However, this process will erase all existing data on the drive. To avoid permanent data loss, it's crucial to recover your files first using a trusted data recovery tool. Once your data is safely retrieved, you can proceed to create a new partition with the partition manager mentioned earlier.

Step 1. Install and start AOMEI Partition Assistant. Right-click the redundant partition and select “Create Partition”.

Step 2. In the small window, you are allowed to change partition size and drive letter of the new drive. Click "Advanced" and choose "Logical Drive". Then click “OK”.

Step 3. Click “Apply”>“Proceed” to start the creation.

Way 5. Delete volume

Lastly, if your external drive contains multiple partitions and one is unallocated, you might want to delete the existing volume next to the unallocated space:

Step 1. Launch AOMEI Partition Assistant. In the main interface, right-click the partition, and choose “Delete Partition”.

Step 2. In the pop-up window, choose “Delete partition quickly without wiping data” or “Delete partition and wipe data on it”. Then, click “OK”.

Step 3. Click “Apply” and “Proceed” to confirm the operation.

Bonus reading: How to recover data from unallocated external drive

When valuable files reside on an unallocated hard drive, the risk of data loss becomes serious. Without a backup, it might feel like everything is gone, but recovery is still possible. AOMEI Partition Assistant for recovery offers a powerful solution to retrieve lost data, even from unallocated space.

Compatible with Windows 11, 10, 8, and 7, this tool supports recovery of over 200 file types, including photos, documents, videos, emails, and more. Whether the data loss is due to accidental deletion, formatting, malware, corruption, or even a system crash, the software provides an effective way to restore what’s missing.

Here’s how to use AOMEI Partition Assistant to recover your data:

Step 1. Begin by installing and launching AOMEI Partition Assistant. On the Main Tab, locate and click "Recover," then select "Recover Data".

Step 2. A window titled "Recover Windows Data" will appear. Identify the partition location from which you wish to initiate data recovery, and then click "Start Scan".

Step 3. Once the scanning process is complete, you'll see a display of all the deleted files, items from the recycle bin, and other missing files. Carefully select the data you want to recover, and then click "Recover".

Step 4. Choose a specific folder path on your PC where you want to save the recovered data.

Step 5. Commence the recovery progress, and upon successful completion of the process, your data will be securely saved to the designated path you selected.

Conclusion

With these available solutions, repairing unallocated hard drive issues in Windows 11, 10, 8, or 7 becomes a straightforward task. So there's no need to panic the next time you run into this kind of problem.

Beyond fixing unallocated disk errors, AOMEI Partition Assistant is also equipped to handle a wide range of other disk issues, such as external hard drive not displaying, I/O disk errors, and more.