Unfortunately, your HDD became unknown and not initialized in Disk Management, you can fix it with these methods: rebuild MBR, initialize the disk, format the drive with Diskpart, turn off the PC and remove the battery, check for connection issues, update the drive driver, and send for manual repair.
There are two cases when your HDD turns unknown and not initialized in Disk Management, the Windows built-in tool. It may be accompanied by unallocated space size or no space size information.
If the external hard drive is unknown, uninitialized, and unallocated, the cause may be the corruption of the MBR(Master Boot Record). In case there is no size of the unknown and not initialized disk, the hardware issue could be the culprit.
In any of these two scenes, your files stored on the drive become inaccessible, and you can not save new contents to it, the whole drive is unusable. Then you can try the fixes below to troubleshoot an unknown and not initialized HDD.
If the drive is unknown, not initialized, and unallocated, you can:
1. Rebuild MBR. Open the Command Prompt and run as administrator, then run the command lines bootrec/fixmbr and bootrec/fixboot.
2. Initialized and format the drive. This will erase all your data and make the drive usable again. It is recommended to recover data from an unknown and not initialized disk before you move to initialize it. You can try iBoysoft Data Recovery for Windows to quickly get your lost/deleted files off and continue to fix the malfunctioned drive without losing data.
If the drive is unknown, not initialized, and has no size, you can:
1. Turn off the computer and remove the battery for more than 10 seconds. Then, insert the battery, restart the computer, and reconnect your drive. This could eliminate the motherboard-related error causing the disk unknown and not initialized.
2. Check the USB port and cable. An unstable and poor connection between the drive and the computer could lead to an unknown and uninitialized drive. Just change to another port or another cable to make sure the connection is in good condition.
3. Update the disk driver. An outdated or corrupted disk driver may also result in an unknown and not initialized drive in Disk Management. Head to the Device Manager in File Explorer, locate and double-click your drive and choose Update driver.
If unluckily, all these methods don't work to fix your unknown and not initialized drive, the drive is probably physically damaged, you can send for manual repair or consider a replacement.