Fix MBR on an External Hard Drive or USB Drive for Free

The Master Boot Record (MBR) contains boot code and partition information on disks using the MBR partition scheme. If the MBR is damaged, a computer may fail to boot from an external hard drive or USB drive.

In this guide, you’ll learn how to rebuild the MBR with MiniTool Partition Wizard. We’ll also explain what to check if the external drive remains inaccessible after the repair.

What Causes MBR Corruption on an External Drive?

MBR damage on an external hard drive or USB drive is usually caused by:

• Unsafe removal or a sudden power loss while data is being written
• Virus or boot sector malware infection
• Interrupted partition operations, disk cloning, or disk conversion
• Bad sectors in the area where the MBR is stored

Fix MBR on External Drive for Free with MiniTool Partition Wizard

MiniTool Partition Wizard includes a Rebuild MBR function for supported MBR-partitioned disks. It can help repair the master boot record when an external drive has an MBR-related boot problem.

The following steps explain how to use this function. Before proceeding, check that the correct external disk is selected and that the disk uses the MBR partition scheme.

How to Fix MBR on External Hard Drive or USB in 3 Steps

If your external hard drive or USB drive uses the MBR partition scheme and has a damaged master boot record, you can try rebuilding the MBR with MiniTool Partition Wizard.

Before starting, confirm that Windows detects the correct disk. If the drive contains important files, back up your data if possible. Do not initialize or format the disk if Windows prompts you to do so and you need to preserve the existing data.

Follow these steps to rebuild the MBR.

Step 1 – Connect the External Drive to Your Windows PC

Connect the external hard drive or USB drive to your Windows PC, then download, install, and launch MiniTool Partition Wizard. Make sure the drive appears in the disk map.

MiniTool Partition Wizard FreeClick to Download100%Clean & Safe

Step 2 – Select Rebuild MBR

Right-click the external drive whose MBR is damaged and select Rebuild MBR. Select the whole disk rather than a single partition, and check the disk number and capacity so you don’t rebuild the MBR of your system disk by mistake.

Step 3 – Apply the Changes to Fix MBR on External Drive

Click Apply in the top-left corner to repair the boot sector on the external hard drive or USB drive. When the process finishes, try booting from the drive or opening it in File Explorer to check whether it is accessible again.

External Hard Drive Repair: What to Do If It Still Fails

If your external hard drive is still not working after you fix MBR on the external drive, try the external hard drive repair methods below. If the drive holds important files that aren’t backed up, recover your data first (method 2).

1. Partition Recovery

If the external hard drive or USB drive is still corrupted and can’t be accessed even if you’ve done the MBR repair operation, you can use Partition Recovery function of this tool to easily recover the lost/deleted partition on the external drive to get all your data back.

Step 1. Connect your external hard drive or USB drive with PC and run MiniTool Partition Wizard.

Step 2. Choose and right-click the external drive and click Partition Recovery.

Step 3. Select the scanning range: Full Disk, Unallocated Space, and Specified Range.

Step 4. Choose scanning methods: Quick Scan, Full Scan. Full Scan will scan every sector of the specified scanning range and it will take more time.

Step 5. Choose all needed partitions. Then existed partitions are already checked. You can tick the recovered lost/deleted partition, and click Finish.

Step 6. Then you can select and right-click the recovered partition and click Change Drive Letter to specify a drive letter for the partition. By doing so, you can see the partition in Windows Explorer.

Through partition recovery, you can recover the lost/deleted partition on external hard drive as well as all data on it.

2. Data Recovery

If your external drive can’t be recovered even if you’ve tried partition recovery, then your external drive may be totally corrupted.

You can also turn to the Data Recovery function of MiniTool Partition Wizard to recover your needed important data and files from the external drive. You can freely choose to recover selected files.

Other powerful killer functions of MiniTool Partition Wizard Pro Ultimate include: move/resize/extend/split/merge/create/delete/fomat/wipe/hide/unhide partition, copy disk/partition, migrate OS to SSD/HD, convert NTFS to FAT, convert dynamic disk to basic disk, space analyzer, disk benchmark, manage dynamic disk, etc.

Over the past 10 years, this program earns many people’s trust and helps them flawlessly deal with disk conversion, partition management, system migration, data recovery, and more demands.

3. Check file system and fix errors

Right-click a partition on the external drive, choose Check File System, select Check & fix detected errors, and click Start. This external hard drive repair software will scan and fix file system errors on the partition automatically.

4. Disk surface test

If the external drive has some bad sectors, it also won’t work.

You can launch MiniTool Partition Wizard and right-click the target connected external drive. Then click Surface Test -> Start Now to check if the disk has bad sector.

If this software finds read errors in the disk, it will mark in Red. If not, it will mark in Green.

For more hard drive repair solutions, please refer: Top 4 Hard Drive Repair Solutions to Fix Hard Drive Windows 10

Conclusion

To fix MBR on an external drive for free, connect the correct MBR disk to a working Windows PC, select Rebuild MBR in MiniTool Partition Wizard, and click Apply.

If the problem remains, check for missing partitions, file system errors, or read errors instead of repeatedly rebuilding the MBR. Back up accessible files and verify the result after making changes.

For questions about using MiniTool Partition Wizard, contact [email protected].