When your PC can't recognise an external HDD, it's often caused by connection issues, outdated drivers, corrupted file systems, or drive damage. This guide explains how to troubleshoot the problem step by step. Whether the drive is not showing up at all or appears as "unallocated," you'll find effective methods here to make your external hard drive detectable again without risking your data.
I can use this external drive on my boyfriend’s PC and my work laptop with no issues. It’s an old drive I’ve used for years, but on my new computer it won’t appear in File Explorer. The system makes the USB sound, detects it in Device Manager, and even shows it in tools like CrystalDisk and SeaTools. I can also safely eject it, but I just can’t access the files.
When an external hard drive is not recognised by a PC, it usually means the system can detect the device at a hardware level but cannot properly mount or display it in File Explorer. This can happen due to issues with connections, drivers, file systems, or even hardware failure.Here are some possible reasons why a PC cannot recognise an external HDD:
❌Connection issues: Damaged or loose USB cable, or faulty USB port not working as normal.
❌Insufficient power supply: Some high-capacity external drives require extra power to function correctly.
❌Driver issues: Outdated, corrupted, or conflicting drivers can prevent the system from recognising the drive.
❌Unsupported file system: Windows cannot natively read Linux-based formats such as EXT4 or Btrfs.
❌Corrupted partition table: A damaged partition table may cause the drive to appear as RAW or unallocated.
❌Unpartitioned or unformatted drive: The disk is detected but has no usable partitions configured.
❌No assigned drive letter: Without a drive letter, the external HDD will not appear in File Explorer.
❌USB ports disabled in BIOS/UEFI: Hardware-level restrictions may block external devices from being accessed.
❌Hardware failure: Aging or heavy use can lead to bad sectors or physical damage.
❌Enclosure controller failure: A defective enclosure controller board can stop the drive from being recognised.
When your PC fails to recognise an external hard drive, try these solutions step by step, fromsimplest checks to some advanced methods to avoid unnecessary data loss.
First, try a different USB cable and replace the current one with a known working cable. If that doesn’t help, switch USB ports and test both USB 2.0 and 3.0 ports on your computer. Also, avoid using USB hubs and connect the drive directly to the PC for a more stable connection.
Some external hard drives, especially high-capacity models, require extra power to operate correctly. Make sure to connect both USB plugs if the drive uses a Y-cable, or use the external power adapter if provided. For desktop PCs, plug the drive directly into the back panel USB ports or a powered USB hub to ensure stable power delivery.
If the new disk does not appear in Windows File Explorer or even Disk Management at all, the issue lies earlier in the detection chain. In this case, you need to force the system to recheck its hardware.The "Rescan Disks" command instructs Windows to immediately scan for any hardware changes on all disk controllers, which can detect a newly connected disk that the system missed during startup or hot-plugging.
Press "Win+X" and select "Disk Management" to open it.
In the menu bar at the top, click on "Action". From the drop-down menu, select "Rescan Disks".
Outdated driver can can prevent your PC from recognising an external hard drivesuccessfully.To update the driver, open Device Manager and expand the sections for Disk drives and "Universal Serial Bus controllers". Locate your external HDD, right-click it, and select "Update driver".
If the problem persists, choose "Uninstall Device" instead to uninstall the driver and restart your computer so Windows can automatically reinstall it.
If your external HDD does not appear in File Explorer but is visible in Disk Management, the issue might be with the drive letter—either it hasn’t been assigned or it conflicts with another drive. In this case, you can assign a new drive letter or change the current one to a different letter.
Open Disk Management, locate your external drive. Right-click the partition, and select "Change Drive Letter and Paths". Click "Add" if there’s no letter assigned, or "Change"to select a new letter from the list.
If your external HDD appears in Disk Management but shows as offline, you can bring the drive online and assign a letter using Command Prompt (or refer to the last method):
Step 1. Press "Win + S", type "cmd", right-click "Command Prompt", and select "Run as administrator".
Step 2. In the Command Prompt, type the following commands line by line, pressing Enter after each:
Replace 7 with the volume number of your drive and J with any available drive letter you prefer.
Next, if the drive still isn’t accessible, you may need to check the file system for errors. A corrupted file system can prevent Windows from reading the drive even if it is detected. You can use CHKDSK for minor error repairs.
Open the Command Prompt window, type the command: chkdsk x: /f
Replace X: with the drive letter of your external HDD. The /f parameter tells CHKDSK to fix any detected errors.
Press Enter and wait for the scan to complete. Depending on the drive size and errors, this may take several minutes.
If your PC cannot recognise the external HDD because its partition table is damaged, you can use the TestDisk tool, a free open-source tool, to rewrite it.
Step 1: Download TestDisk from the official website and extract the files. Run "testdisk_win.exe" as administrator to launch the program.
Step 2: Choose "Create" to start a new log file, then select your external HDD from the list of drives and press Enter.
Step 3: Select the disk and partition table type detected by TestDisk, usually Intel/PC for MBR disks or EFI GPT for GPT disks.
Step 4: Select "Analyse" to scan the drive for existing partitions. TestDisk will display the detected partitions.
Step 5: Review the partitions using the arrow keys and press P to list files in a partition to verify your data is intact.
Step 6: If the partitions are correct, choose "Write" to save the repaired partition table and confirm the action.
Safely disconnect and reconnect the external HDD, then check File Explorer to see if the drive is now recognized.
If all previous methods fail and your PC does not recognise external hard drive, reformatting the drive may be the final solution. Reformatting will erase all existing data and create a new file system, allowing Windows to read and write to the drive properly.
Before proceeding, ensure that any important data has been recovered using data recovery software like MyRecover, as reformatting will permanently delete all files.
After successfully recover files from the unrecognized external drive, you can use Disk Management or DiskPart tool to reformat it to a compatible file system.
To format the disk using DiskPart, just run the following commands:
If your external HDD is still not recognised, the issue may be at the hardware or firmware level. Restart your PC and enter the BIOS/UEFI settings by pressing the designated key during boot (commonly Del, F2, F10, or Esc, depending on your motherboard). Once in BIOS/UEFI, navigate to the USB Configuration or Peripherals section and make sure all USB ports are enabled.
After making changes, save the settings and restart your computer. This can often resolve recognition issues caused by disabled or restricted USB ports.
When your PC cannot recognise external HDD, you can try the above methods in this article. Before repairing the file system or reformatting it, we highly recommend recovering files with MyRecover. As a powerful data recovery software, it can help recover data from unbootable system, emptied Recycle bin, deleted partition, formatted partition, virus attack, power failure and more.