What is a corrupted file?
A corrupted file is a computer file that has become damaged, unusable, or unreadable. File corruption happens when the data in a file is unintentionally changed or destroyed, rendering the file partially or fully inaccessible. Some common causes of file corruption include:
- Hardware problems like bad sectors on a hard drive or faulty RAM
- Forced shutdowns, power outages, or improper system reboots during a file transfer
- Software crashes, bugs, or errors
- Viruses, malware, or harmful software
- Improper file transfers or interrupted networking
File corruption often occurs without warning and can affect many different file types like documents, photos, videos, and more. The file contents may display incorrectly, fail to open, or be partially or fully unreadable by software. Trying to access a corrupted file can sometimes cause apps to crash or freeze.
Detecting and repairing file corruption early is key to minimize permanent data loss. Warning signs of corruption include strange file sizes, trouble opening a file, or error messages noting the file is corrupt or damaged. Understanding common corruption causes can help avoid and identify file damage.
Identify the Corrupted File
There are several signs that indicate a file is corrupted. The most obvious sign is if you try to open a file and get an error message stating the file is corrupted, damaged, or unable to open. Error messages may vary depending on the application, but often contain wording like “File is corrupted” or “Unable to read file.”
Other signs of corruption include:
- The file crashes or closes unexpectedly when trying to open it
- The contents of the file seem garbled, incomplete, or don’t match what you expect
- The file size is smaller or larger than expected (see https://shredcube.com/corrupted-file/)
- Certain parts of the file won’t open or are missing
- You can’t access or edit the file properly with the associated application
If a file exhibits any of these behaviors, it likely has become corrupted and will need to be repaired before it can be opened and used properly again.
Try opening the file again
Sometimes simply re-opening the file can fix errors and make the file usable again. When a file becomes corrupted, it may just be that some of the data got scrambled while it was open. By closing the application and re-launching it to reload the file, you may find the corruption was temporary and now it opens just fine.
To try this, close the application that shows the file corruption error message. Then re-launch the application and use File > Open to browse to the location of the corrupted file and open it again. Often the file will open normally without issue. If it still shows as corrupted, then the errors are more serious and you will need to move on to the next steps for repairing the file.
Check the file size and format
One way to identify a potentially corrupted file is to check its file size and extension. A corrupt file may show an unexpected size – either much smaller or larger than normal for that file type. For example, a 5MB JPEG image suddenly showing a size of 0KB could indicate corruption. Or a text document displaying a size of 2GB is likely not valid.
Additionally, verify that the file extension matches the apparent format of the file. If the extension is .doc but the file does not open in Word properly, there may be an issue. The metadata may have become scrambled, assigning the wrong extension that does not match the true format.
On Windows 10, right click the file and select Properties. Look at the file size and extension details shown. Compare it to your expectations and other similar files to identify any red flags of potential corruption.
While file size and format can sometimes detect corruption, they are not foolproof ways to validate a file’s integrity. Further scanning and analysis would still be required to fully confirm and diagnose the corruption issue.
Scan for viruses
Viruses can sometimes corrupt files by inserting malicious code that damages the file data. Anti-virus software can scan for known viruses and help remove infections. According to this source, detecting virus corrupted files has become easier with modern anti-virus tools. Run a full system scan with your anti-virus software to check if any infected files are causing the corruption. The anti-virus may be able to repair the files by removing the virus code. If the anti-virus identifies the corrupted file as infected, deleting it can remove the virus before restoring the file from a backup.
Verify the storage device
One potential cause of file corruption is issues with the storage device itself, such as bad sectors on the disk. Bad sectors are areas of the disk that can no longer reliably read or write data due to physical damage or degradation. When the drive attempts to read or write data in these bad sectors, it can cause the data to become garbled or corrupted.
To check for bad sectors, you can use the built-in error checking tool in Windows called CHKDSK. To run CHKDSK, open the Command Prompt as administrator and type “chkdsk X: /f” where X is the letter of your drive. The /f parameter tells CHKDSK to fix any errors found. CHKDSK will scan your drive and attempt to repair any bad sectors.
There are also third party tools you can use such as HDD Regenerator or Hard Disk Sentinel which will do a more thorough scan for bad sectors. If many bad sectors are found, it’s a sign the disk is failing and should be replaced. A failing disk can progressively cause more data corruption over time.
Replacing the disk or SSD can resolve file corruption if the issue stems from bad sectors. Solid state drives (SSDs) develop bad blocks and may need replacement after extensive use. Using quality storage media from reputable brands can help minimize bad sectors.
You can find additional troubleshooting tips on sites like Reddit.
Use data recovery software
Data recovery software is designed specifically to help repair and restore corrupted files. There are many excellent data recovery programs available that can dig deep to salvage your files from even severely corrupted media.
Some top data recovery tools include Stellar Data Recovery, EaseUS Data Recovery Wizard, and Prosoft Data Rescue for Mac. These programs use advanced scanning algorithms to locate files on corrupted drives and reconstruct them to a usable state.
Data recovery software often works when all else fails. They can bypass the file system entirely to scan the raw data on a drive and rebuild file tables and directory structures. This allows recovering data even from drives with corrupted partitions or file systems.
The best data recovery software is inexpensive compared to the value of lost files and provides an essential tool for any computer user. When facing a corrupted drive, data recovery software should be one of the first options to try before attempting any advanced manual file repairs.
Restore from backup
One of the best ways to recover an uncorrupted version of a file is to restore it from a backup. Most operating systems like Windows and macOS have built-in backup utilities that regularly create system backups. There are also third party backup software solutions like Acronis True Image that can be used to schedule regular file backups.
To restore a file from a backup on Windows 10 or 7:
- Open File Explorer and navigate to the folder where the corrupted file was located.
- Right click in the folder and select “Restore previous versions”
- In the file versions window, select the last version of the file created before it became corrupted.
- Click “Restore” to recover that uncorrupted version of the file.
For Mac users, Time Machine backups can be browsed from Finder to find previous uncorrupted versions of a file. Third party backup software like Acronis also includes tools to directly restore individual files from backup images. The key is having regular backups in place so you can roll back to a working version of the file before the corruption occurred. Checking backup logs can help identify the last usable version.
Sources:
How to Restore a File from Automatic Backups – https://www.optuma.com/kb/optuma/troubleshooting-and-faqs/troubleshooting/how-to-restore-a-file-from-automatic-backups
Not able to restore file from backup – https://community.hpe.com/t5/storeever-tape-storage/not-able-to-restore-file-from-backup/td-p/4794916
Manual file repair
Manually repairing a corrupted file is an advanced method that requires technical expertise. However, it may allow you to recover files when all else fails. This method involves using a hex editor or binary editor to directly view and manipulate the raw data of a file.
To start, open the corrupted file in the hex editor. The file will appear as hexadecimal code. Carefully analyze the code to identify errors like incorrect magic numbers, invalid headers or footers, or out-of-order segments. With patience and knowledge of the file format specifications, you may be able to correct errors in the hex code to repair the file structure.
Some common repairs include fixing the file header which contains crucial metadata, repairing the file allocation table which indexes file segments, or reconstructing corrupted chunks of raw data. Be very careful when editing hex code as any mistakes could further damage the file. Consider working on a copy in case your changes cause additional harm.
If you have the skills to dive into hex editing, manual repair can sometimes salvage files from extreme corruption. However, it requires high technical expertise and a solid understanding of the target file type structure. For most users, automated recovery software or professional recovery services are a safer choice over DIY hex editing.
Source: https://www.easeus.com/file-recovery/repair-corrupted-files.html
When all else fails
If you have exhausted all options to recover the corrupted file and determine it is unrecoverable, there are a few final things you can try:
Contact the creator of the file if possible and ask them to resend an uncorrupted version. The original may exist on their computer or in a backup.
Search online for resources specific to recovering that file type. There may be specialized software or manual techniques for certain formats like PDFs, Excel spreadsheets, or video files.
As a last resort, accept the file is unrecoverable and focus efforts on recreating or finding a replacement. If it contained vital information, try recalling the key details and make notes. Reconstructing even parts could be worthwhile.
Analyze how the file was corrupted to prevent it happening again. For example, it could be due to a faulty storage device, malware infection, or program crash. Understanding the cause can help avoid future file corruptions.
While losing important or sentimental data is frustrating, ultimately unrecoverable files may need to be accepted as permanent losses. Moving forward productively, rather than dwelling on the unchangeable past, is often healthiest.