how to fix a corrupted external hard drive

Recover Files From External Hard Drive Without Formatting

Why Do Hard Drives Become Corrupted?
How to Restore Data from External Hard Drive Without Formatting?
- Step 1. Scan Your Computer for Viruses
- Step 2. Use CHKDSK to Fix File System Errors
- Step 3. Replace Corrupted Files with SFC
- Step 4. Recover Your Files with Data Recovery Software
Symptoms of External Hard Drive Corruption
Tip: Don't Forget to Frequently Back Up Your Data

Why Do Hard Drives Become Corrupted?

There are many reasons why your external hard drive may trigger the "You need to format the disk before you can use it" pop-up window, and you need to understand at least the most common ones to determine the best data recovery approach.

Read/write issues: Traditional spinning hard drives are complex electro-mechanical devices that rely on the interaction of platters traveling anywhere from 5,400 to 12,000 RPM and delicate read/write heads hovering just a few nanometers above them. Anything from regular wear and tear to minuscule debris floating inside the hard drive enclosure can result in read/write issues and cause hard drive corruption and errors.
Software bugs: Files stored on a healthy hard drive can become corrupted because of software bugs. In such cases, corruption tends to be limited to the files accessed by the buggy software. However, things can become very bad if the buggy software has admin privileges and access to system files.
Virus damage: While most viruses and other kinds of malware don't corrupt data, some are programmed to do just that and cause as much damage as possible by deleting important system files or encrypting personal data. A reliable antivirus should be able to catch most viruses dead in their tracks, but your first line of defense should always be caution and common sense.
Manufacturer faults: Even the largest and most reputable hard drive manufacturers make mistakes and occasionally release a hard drive that requires a firmware update to work properly. It's a good idea to check online if there isn't an update available for your hard drive or if it hasn't been recalled.
Poor operating conditions: Hard drives require certain operating conditions to work properly and reliably. Excessive heat, high humidity, or electrical surges can significantly reduce their lifespan or instantly cause damage, depending on their severity.

How to Restore Data from External Hard Drive Without Formatting?

Step 1. Scan Your Computer for Viruses

To scan your computer for viruses, you don't need to download any third-party antivirus software solution. You can simply use Windows Defender, which is included in all recent versions of the Windows operating system and outperforms even paid solutions.

To scan your computer for viruses with Windows Defender:

Type "windows security" in the Taskbar search box and press Enter.
Select Virus & threat protection from the menu on the left.
Select Scan options under Quick scan.
Choose Full scan and click the Scan now button to check all files and running programs on your hard drive.

Step 2. Use CHKDSK to Fix File System Errors

First released in 1980, CHKDSK (short for check disk) is a command-line tool capable of listing and correcting disk errors. When used with the appropriate parameter, it can check the disk surface for bad sectors and mark them accordingly. After fixing all disk errors with CHKDKS, you should be able to access your external hard drive without formatting.

To fix logical file system errors with CHKDSK:

Type "cmd" in the search box on the taskbar and select Run as administrator.
Enter the following command (make sure to replace X with the letter assigned to the hard drive you want to fix) and press Enter: chkdsk X: /R
Wait for CHKDSK to finish. The process may take several hours depending on the size of your hard drive.

The /R parameter tells CHKDSK to checks the entire disk surface for bad sectors and repair them if possible.

Step 3. Replace Corrupted Files with SFC

The Windows System File Checker (SFC) is a command-line tool for repairing corrupted system files in a Windows installation. A corrupted Windows installation may behave erratically and make it impossible for you to access your external hard drive.

To replace corrupted files with SFC:

Type "cmd" in the search box on the taskbar and select Run as administrator.
Enter the following command and press Enter: sfc /scannow
Wait for SFC to finish. The process usually takes around an hour.

Step 4. Recover Your Files with Data Recovery Software

If you still can't access your external hard drive without formatting, you should use a software solution like Disk Drill Hard Drive Recovery to recover all important files from it. Disk Drill supports all major file systems (NTFS, FAT, FAT32, exFAT, EXT3/EXT4/, HFS, APFS) and lets you recover up to 500 MB for free.

To recover your files from an external drive using software:

Download and install Disk Drill.
Connect your external hard drive to your computer.
Launch Disk Drill, select the external hard drive, and click Search for lost data.
Wait for scanning to finish.
Preview and select the files you want to recover.
Click the Recover button at the bottom.
Select the recovery destination and click OK.

Disk Drill for Windows & macOS Free Download

Symptoms of External Hard Drive Corruption

You can avoid having to restore data from your external hard drive if you learn to recognize early signs of hard drive corruption.

Hard drive not recognized: When you connect your external hard drive to your computer, it should be instantly recognized every single time. If the hard drive is sometimes not recognized, it might be corrupted, and you should back up your data as soon as possible.
Strange sounds: Do you sometimes hear clicking, whirring, or whining noises when using your external hard drive? If so, the hard drive might be developing a mechanical problem that could cause it to stop functioning at any moment.
Wrong hard drive size: It's normal for a 1 TB hard drive to have an actual capacity of just 931 GB because hard drive manufacturers market drives in terms of decimal capacity. But if your external hard drive is missing an unexplainably large amount of storage capacity, there's probably something wrong with it.
Missing or unreadable files and folders: This telltale sign of hard drive corruption is easy to overlook because modern hard drives can store millions of files, making it impossible to check each file manually. Fortunately, there are software solutions like CHKDSK that can scan your entire external hard drive and detect corrupted files and folders.
Poor performance: Your hard drive should be able to reach its specified read/write speed. Constant performance problems can be caused by the hard drive trying to overcome file system corruption, so you shouldn't ignore them.

Tip: Don't Forget to Frequently Back Up Your Data

recover files from external hard drive without formatting

Your hard drive can become corrupted at any time, and you might not always be able to fix it using the above-described methods. To prevent data corruption from ruining your date, you should frequently and regularly back up your data to another storage device.

You can either back up specific files or use Disk Drill to create a byte-to-byte copy of your entire hard drive. The main advantage of having a byte-to-byte hard drive copy is that you can use it to easily recover all your data, applications, and settings even if your hard drive stops working completely.

To create a byte-to-byte hard drive copy with Disk Drill:

Launch Disk Drill and select Drive Backup from the Extras menu on the left.
Watch the video instructions to learn more about the Drive Backup feature or click the "OK, let's do it" button to continue.
Select the partition you would like to back up and click Backup.
Choose where you want to save the backup disk image and click Save. Make sure to select a hard drive with enough storage space.
Wait for the backup process to finish.

FAQ

The data recovery software solution we described earlier in this article, Disk Drill, is available both for Windows and Mac computers. This is what you need to do to recover files from an external hard drive with Disk Drill for Mac:

Download and install Disk Drill for Mac.
Connect the external hard drive to your Mac.
Launch Disk Drill and click the recovery button next to the external hard drive.

Windows To Go provides an easy way to make Microsoft-certified external NTFS hard drives bootable. This feature is available in Windows 8 Enterprise, Windows 8.1 Enterprise, Windows 10 Education, and Windows 10 Enterprise, and this is what you need to do to access it:

Open the Control Panel.
Set the View by option located under the search box to Small icons.
Select Windows To Go.

Yes, Disk Drill is designed to be 100% safe even when used by users with limited data recovery experience. All of its options are completely self-explanatory, and its powerful scanning algorithms remove all the complexity from data recovery while delivering professional results.