Repair Corrupted System Files and Prevent Data Loss in Windows 7

You will learn 4 helpful ways to repair system files in Windows 7, 8, 10, 11 and how to effectively prevent this error and data loss due to it.


By Ivy Updated on October 20, 2022

Share this: instagram reddit

What is a system file?

A system file is an important computer file, as its name implies, without which or it's damaged, a computer system may not work correctly. It usually comes as part of the operating system for its core operations.

And Microsoft Windows mark these system files with a "system" attribute to protect them against mistaken deletion. And it’s located in a system folder, such as, C:\Windows\System32.

System files corrupted or missing: how to identify and why

Like a corrupted file, if something goes wrong with it, you will lose access to it. If you try to open it, you will receive an error message that implies the file is corrupted or damaged. If the file is a system file, the situation may become much worse, such as, you may encounter a blue screen, saying, "your PC ran into a problem and needs to restart".


Besides Windows errors, the corrupted files sometimes are much smaller than they should be. Also, you can compare the potentially corrupted files to another file of a similar type for identifying.

Afterward, you may be eager to the causes for this error. In fact, behind corrupted or missing system files, there are many reasons, such as, computer crashes, sudden power drops or surges, update errors, disk problems, third-party programs, virus attacks, human error.

How to repair Windows if system files are corrupted or missing

After identifying the system files are damaged and its potential reasons, you can repair system files using cmd. The system file checker is the best way to start the troubleshooting.

It's Windows 7 system files repair tool to scan your computer for corrupted system files and attempts to restore any it finds. And all of the following methods also apply to other systems, including Windows 8, 10, 11. You can try it first and then other ways.

#1: System files integrity check and repair Windows  7

  1. Type cmd in the search box and then select Run as administrator.
  2. Type sfc /scannow in the command prompt and hit Enter.

SFC Scannow

After the sfc /scannow end, you may get if the system repair is fixed or not. If it says "Windows Resource Protection could not perform the requested operation", you can repair system files in safe mode or using CD/DVD that comes with your computer if your computer still have trouble. You can directly press Shift +F10 to open command prompt in the Windows Setup window. 

Besides, you still can receive that there are still some unrepaired system files with error messages like “Windows Resource Protection found corrupt files but was unable to fix some of them. Details are included in the CBS.Log %WinDir%\Logs\CBS\CBS.log. ”.  You can view the SFC log for corrupted files and it will be introduced in the next way. 

#2: View SFC log and repair system files manually

In this case, you should create a SFC log file with the CBS log file, then find the corrupt or missing Windows file and replace it with a good one.

★ Create and View the SFC log file

  1. Open cmd as administrator, enter the following command in the pop-up window and then hit Enter. This operation can help you create a sfclogs.txt file on the desktop.

▶ findstr /c:”[SR]” %windir%\Logs\CBS\CBS.log >”%userprofile%\Desktop\sfclogs.txt”

  1. Open the sfclogs.txt file, find the date and time entry for a file that could not be repaired.
The Sfcdetails.txt files use Date/Time SFC details format, thus you need to verify the date and time entries. Then, you can use it to find the unrepaired files.

★ Repair damaged system files in Windows 7

  1. Find known good system files copies on another computer with the same version of the operating system.
  2. Open CMD as administrator.
  3. Type the following command to take ownership of the corrupted files and hit Enter to run it.

▶ takeown /f C:\Windows\System32\appraiser.dll

C:\Windows\System32\appraiser.dll refers to the path and name of the corrupted system file. You should replace it.
  1. Type the command below to give a full admin access to the corrupted files and then hit Enter.

▶ icaclsC:\Windows\System32\appraiser.dll /Grant Administrators:F

  1. Type the following command to replace the damaged system files and press Enter.

▶ copy D:\Files\appraiser.dll C:\Windows\System32\appraiser.dll

▶ takeown /f C:\Windows\System32\appraiser.dll

D:\Files\appraiser.dll refers to the path and name of the known good file. You should replace it.
  1. Type yes in the window and then Press Enter.
  2. Type sfc /verifyonly command to check the integrity of all the system files and press Enter to move on. Wait until the process is 100% complete.

#3: Windows 7 missing files repair online via DISM

Besides SFC, you still can try DISM command utility in Windows 8/10 to automatically fix SFC Scannow not working. And it will scan and repair system files in Windows 8/10.

  1. Run cmd as administrator.
  2. Type the following command in the pop-up window and hit Enter.

▶ DISM /Online /Cleanup-Image /RestoreHealth

Windows 7 Missing System Files Repair Online

#4: Repair Windows 7 system files without CD

System Restore is a great choice if you cannot repair Windows 7 still now. It's to restore system files, Windows Updates, settings, and applications to an earlier state. And It’s easy to learn and operate, you can try it with the following steps.

  1. Type system restore in the search box and select it.
  2. Select Recommended restore, and follow the wizard until the last step. If the recommended restore point is not available, you can try another restore point by ticking Choose a different restore point.

System Restore

Effective tips: always keep system files in a safe way

System files are crucial to ensure your computer works as it is supposed to, thus, it's necessary to create a system image backup after repairing system files in Windows 7, which will include all of the system files. And you can easily restore your computer to a previous good state if you have a system image, even if your computer crashes, not to mention the corrupted system files. And all the computer failures can be solved completely.

Then, how to make it? You need the best free backup software - AOMEI Backupper Standard. With it, you can backup system to external hard drive, USB drive, cloud drive like Dropbox, Google Drive, etc. And below are useful useful features you can use:

Schedule Backup: You are allowed to set backup frequency for this task, including Daily, Weekly, Monthly. 
Backup Scheme: You can choose to backup only changes on the system partition with its Incremental Backup instead of making a full system every time. 
Options: You can comment on task, enable email notification, compression, splitting, intelligent sector backup, VSS backup mode, etc.
Various System support: Windows 11/10/8.1/8/7/XP/Vista.

Now, follow the steps below to backup system:

  1. Download free AOMEI Backupper Standard, install and launch it. If you are a Windows Server user, please turn to AOMEI Backupper Server. Click Backup and System Backup to start the operation.
Download Freeware Win 11/10/8.1/8/7/XP
Secure Download

System Backup

  1. The system-related partition will be selected by default.  Move you mouse to the second box and click the folder-shapped button to select the destination path for backup.

Select Destination

  1. Confirm this operation and click Start Backup to backup system in Windows.

After the backup created successfully, you can use it for corrupted system files repair or other computer failure. Go to the Restore tab, choose Select Task, then find your image and select destination, click Start Restore. 

If you cannot see any backup image in the Restore tab, go back to the main page of Restore tab and choose Select Image File as instead.

Select Task


▶ If your image is saved on the external hard drive and the computer is unbootable, you need to create a bootable disk first with its Create Bootable Media tool. And then, connect the drive containing your backup image and boot from it . At last, you can restore image from external hard drive based on instructions.

Create Bootable Media

▶ Alternatively, you can create a recovery environment on your computer ahead of time. Once the recovery environment is created and enabled, the "AOMEI Backupper Recovery Environment" option will be added to the system boot menu page so that you can select to start the system from the recovery environment to restore images created by AOMEI Backupper.

Recovery Environment Settings

Another reliable backup software to protect your system and system files

Except for AOMEI Backupper Standard, you still can try one key recovery software -  AOMEI OneKey Recovery. The difference is that this software allows you to save system images on a hidden recovery partition, which greatly avoids mistaken deletions and data loss risk. 

And it enables you to set fast key ("F11" or "A") or boot menu to access this software quickly, even when it's slightly damaged.  In addition, it not only supports Windows 7/8/10/11, but also supports Windows Server 2003/2008/2012/2016/2019/2022 including the R2 version. All operations are quite simple.

To backup system files, just choose OneKey System Backup after launching AOMEI OneKey Recovery. Then, select a way to backup your system and where to save it. Finally, click Start Backup

OneKey System Backup

Also, you can set compression or password protection for it. And backup frequency (daily, weekly, monthly) are also supported.

Set Schedule Backup

Wrapping things up

This article is the right place if your system files are corrupted. It provides you with 4 helpful ways to repair system files in Windows 7. And them also applies to Windows 8/8.1/10/11. 

If you don't want to lose any data due this error or any other computer failure, you still need to create a complete system backup in Windows with AOMEI Backupper Standard or AOMEI OneKey Recovery, preferably a scheduled one. Since it will retain all of your changes util the recent one you create.

For advanced users, you still can do system clone to HDD/SSD with AOMEI Backupper. It can achieve the same effect, but the process is simpler. You just need to clone system once, and use it to replace hard drive directly, no restore required before using. If needed, please upgrade to AOMEI Backupper Professional first.

Ivy · Editor
Ivy is an editor of AOMEI Technology, she covers backup & restore,hard disk & partitions management and cloud files transfer and so on for AOMEI. She is an outgoing girl and enjoys helping people find solutions to their problems. She loves traveling, eating, reading and so on. She usually hangs out with friends at her leisure time.