How to fix disk unknown not initialized in Windows 10/8/7?

Updated by Tim to Data Recovery Tips on April 23th, 2020

I have WD external hard disk connected via USB and it does not get detected in Windows explorer. Checked disk management where it shows disk as "Unknown" and "Not initialized". I don't want to lose any data, it contains all my family photos, please help.

Three disk unknown not initialized situations

1. Disk 1 unknown, not initialized, no size or no disk space. In this case, it is a harware issue.

Disk unknown not initialized, no disk space

2. Disk 1 unknown, not initialized, unallocated space

Disk unknown not initialized unallocated

3. Disk unknown, not initialized, I/O device error. In this case, it is a harware issue.

Windows Disk Management shows an error: disk unknown not initialized on the hard disk, external hard drive, USB drive, flash drive, SD card, etc, the disk may show "unallocated space" or no disk space in Disk Management, so you are not able to access data stored on this uninitialized disk, which makes you very upset and don't know how to solve this issue and recover lost data.

Why is disk unknown not initialized?

Generally speaking, there are several reasons cause disk unknown not initialized:

1. Virus attack: Sometimes external hard disk is unknown not uninitialized because of virus infection.

2. Bad sectors: If there are bad sectors on the storage device, Windows OS fails to read the partition table information from the first sector and load the partition table, Disk Management will show disk unknown not uninitialized.

3. MBR corruption: The MBR (Mast Boot Sector) code and partition table are written in the first sector of the disk. Once MBR is corrupted, disk will be not unknown not uninitialized and Windows OS fails to access the data stored on this disk.

4. Partition loss: when partition is lost or deleted, disk unknown not initialized issue may happen.

5. Hardware issue.

How to fix 'disk unknown not initialized, unallocated space'?

Firstly open Windows Disk Management and find the uninitialized disk. If this uninitialized disk shows disk capacity, it means your Windows OS has recognized this uninitialized disk, but the partition is lost/deleted or MBR is corrupted due to some reasons. In this case, you need to fix/rebuild MBR and recover the deleted/lost partition.

After knowing the above methods, it is time to fix disk unknown not initialized issue with the following solutions:

Solution 1: Initialize the hard disk

If the disk unknown not initialized issue appears in Disk Management, the first thing you may do is to initialize the target disk. However, initialization would erase all disk data, please make sure if there is important data stored on this uninitialized disk before initializing.

If there is importanta data stored on it, you need recover lost data from the uninitialized disk first and then initialize the target disk after data recovery is successfully done.

M3 Data Recovery is a free data recovery software which supports to recover lost data from the uninitialized disk, recover lost data from the formatted, RAW, inaccessible, corrupted, lost, deleted partition, recover lost data from Bitlocker encrypted drive, etc.

Please follow below steps to recover lost data from the uninitialized disk:

Step 1: Download and install M3 Data Recovery software on your Windows computer.

Step 2: Connect the uninitialized disk to your Windows computer as external drive.

Step 3: Launch M3 Data Recovery software and choose Data Recovery module.

Free data recovery software

If the drive is Bitlocker encrypted, please choose Bitlocker Recovery module to recover lost data from Bitlocker encrypted drive.

Step 4: Click "Find More Partitions".

M3 Data Recovery

Step 5: Select the uninitialized disk and click Next to scan for lost partitions.

Scan lost partitions

Step 6: Select the lost partition and click Next to scan the lost data.

Scan lost data from the lost partition

Step 7: After the scan completes, the lost files will be listed as below window, then select the files you want to recover and start recovery.

Recover lost data with M3 Data Recovery

After data recovery from the uninitialized disk, please follow below steps to initialize this disk:

Step 1: Right click My Computer or This PC.

Step 2: Select Manage from the right-click menu -> Storage -> Disk Management.

Step 3: Right click this target disk and select "Initialize Disk".

Select Initialize Disk

Step 4: In the Initialize Disk window, check to make sure that the correct disk is selected and then select the partition style: MBR or GPT.

Initialize Disk

Step 5: Click Ok to initialize this disk.

After this disk is initialized, you can repartition it according to your needs. If you receive I/O device error when initializing, it means there is a hardware issue on the uninitialized disk.

Solution 2: Fix/Rebuild MBR

MBR corruption may cause disk unknown not initialized issue, in this case, fixing/rebuilding MBR is the quick way to solve disk unknown not initialized issue, there are some the 3rd-party tools (Such as Aomei Partition Assistant, MiniTool Partition Wizard) which have the function to fix/rebuild MBR.

Step 1: Download, install and launch Aomei Partition Assistant.

Step 2: Right click on the uninitialized hard drive and then select "Rebuild MBR".

Step 3: Select the MBR type for your OS and click "OK".

Step 4: Click "Apply" button to fix/rebuild MBR.

Solution 3: Partition recovery

Sometimes partition loss would cause disk unknown not initialized issue, if you find disk shows unknown, not initialized, unallocated space in disk management, in this situation, the best way is partition recovery - Find deleted/lost partition and then recover lost data. M3 Data Recovery also supports to recover lost data from deleted/lost partition.

Solution 4: A local data recovery specialist

A hardware issue can also cause disk unknown not initialized error. If there is no disk space in storage media or you encounter disk not initialized I/O device error, it means the hard disk has a hardware issue. In this case, hardware issue is beyond any data recovery software, please send it to a local data recovery specialist.