Windows 11 is stable for most users, but sometimes even the best-maintained systems start showing strange symptoms — random errors, lag, slow performance, corrupted apps, or general instability. When this happens, many people immediately assume that a full system reset or reinstall is the only option. Fortunately, that’s not true.
Windows 11 includes two powerful built-in repair tools — DISM (Deployment Image Servicing and Management) and SFC (System File Checker) — that can automatically scan and repair damaged system files.
If any essential Windows component becomes corrupted, these tools replace it with a fresh, healthy version. The best part? You don’t need third-party software, and you don’t lose your files.
In this detailed guide, we’ll walk through everything step by step, explain why each command matters, and cover alternative methods in case something doesn’t work. Along the way, you’ll see helpful notes, real-world examples, and a few warnings that you should keep in mind.
Before we start, here’s a simple disclaimer:
Disclaimer: This guide is safe for all Windows 11 users, but you should avoid interrupting the repair process once it begins. Always keep your laptop plugged in during these steps.
Now let’s begin.
1. Understanding DISM and SFC
Before running any commands, let’s take a moment to understand what these two tools actually do. Knowing this will help you troubleshoot better and understand the repair process more clearly.
DISM (Deployment Image Servicing and Management)
DISM is responsible for checking and repairing the Windows image. Think of the Windows image as the core foundation of the operating system. If this core becomes damaged, every part of Windows — including File Explorer, Settings, Start Menu, and apps — can get unstable.
DISM fixes:
- Damaged Windows system image
- Corrupted component store
- Missing essential system files
- Problems caused by failed Windows Updates
It does this by downloading clean files from Windows Update or, if that fails, from a Windows 11 ISO file.
SFC (System File Checker)
SFC scans and repairs the actual system files in use on your computer. It checks every protected file and compares it with the internal Windows image.
If a file is corrupted, SFC replaces it with a healthy version.
How They Work Together
- DISM repairs the Windows image.
- SFC repairs system files using the image.
This means you should always run DISM first, and SFC second.
Now that we understand the basics, let’s move to the next step and actually run the commands.
2. Preparing to Run DISM & SFC
Before we enter these commands, let’s make sure your system is ready. This avoids common errors and ensures the repair process completes smoothly.
What You Need:
- A stable internet connection
- Windows 11 installed
- Administrator access
- (Optional) A Windows 11 ISO file (for advanced repair)
Why Internet Is Important
DISM uses Windows Update to download clean versions of damaged files. If your PC isn’t connected to the internet, the command may fail.
If you don’t have internet, you can still repair Windows using a Windows 11 ISO — we’ll cover that later.
Now that the basics are clear, let’s move on to the first major step.
3. Step 1 — Run Command Prompt as Administrator
Before running repair commands, you must open the Command Prompt with elevated permissions. Here’s how:
So far, we’ve prepared the system. Now let’s actually open the tool we need.
Steps:
- Open the Start menu.
- Type Command Prompt or Windows Terminal.
- Right-click on it.
- Select Run as administrator.
A black window with administrative access will appear. Make sure the window title says “Administrator: Command Prompt” before proceeding.
4. Step 2 — Run DISM RestoreHealth Command (Online Repair)
Now let’s move to the heart of the repair process: the RestoreHealth command.
This command scans the Windows image and repairs it using files downloaded from Windows Update.
Before We Proceed…
Here’s a small but important tip: This command takes time.
Depending on your system and internet speed, it can take between 10-30 minutes.
Do not close the window or restart your PC during this process.
Run This Command:
DISM /Online /Cleanup-Image /RestoreHealth
Press Enter and wait patiently.
What This Command Does
- Scans the system image
- Repairs damaged components
- Downloads healthy replacements
- Verifies file integrity
Important:
Your PC must be connected to the internet for this command to work.
When it finishes successfully, you should see:
“The operation completed successfully.”
If you see this message — congratulations — your core Windows image is now repaired.
But if the command fails, don’t worry. There’s another method.
5. Step 3 — Use DISM with a Windows 11 ISO (Offline Repair)
If the online restore fails (due to network issues, corrupted update services, or blocked download servers), you can use a Windows 11 ISO file as the repair source.
Let’s walk through this step-by-step.
Download Windows 11 ISO (Official)
Before listing the steps, let me clarify something important:
You must download the same version of Windows 11 that you are currently running.
To download the ISO:
✔ Microsoft’s official download page:
https://www.microsoft.com/software-download/windows11
Steps:
- Scroll to Download Windows 11 Disk Image (ISO).
- Select your version (e.g., Windows 11, Version 25H2).
- Choose your language.
- Click Download.
- Save the file to your computer.
Once downloaded, let’s mount it.
Mounting the ISO File
Let’s move to the next step of offline repair.
Steps:
- Locate the downloaded .iso file.
- Right-click on it.
- Select Mount.
Windows will create a new virtual drive (example: D:).
Make note of that drive letter — we will need it.
Running DISM with the ISO Source
Now run this command in Command Prompt (replace D: with your actual ISO drive letter):
DISM /Online /Cleanup-Image /RestoreHealth /Source:D:\Sources\install.wim /LimitAccess
What This Does:
- Uses the installation image inside the ISO
- Replaces damaged system image components
- Skips Windows Update (thanks to
/LimitAccess)
This method also takes some time, so be patient.
Once you see “Operation completed successfully,” your Windows image is fully repaired.
Now we’re ready for the next phase.
6. Step 4 — Run SFC to Repair Active System Files
Now that the Windows image is healthy, it’s time to repair the actual system files.
The SFC command scans every protected OS file and replaces corrupted ones with the clean copies provided by DISM.
Let’s Move to the Next Step…
In the same Command Prompt window, run:
sfc /scannow
Then press Enter.
What Happens Here
- SFC compares every file to the Windows image
- If it finds corruption, it replaces it
- It may take 10–20 minutes depending on system speed
When finished, SFC will display one of these messages:
- Windows Resource Protection did not find any integrity violations.
→ Your system files are perfect. - Windows Resource Protection found corrupt files and repaired them.
→ Excellent; the issue is fixed. - Windows Resource Protection found corrupt files but could not fix some of them.
→ You should run SFC again or use Safe Mode (explained next).
7. Step 5 — If SFC Fails, Run It in Safe Mode
Before diving into steps, let’s understand why Safe Mode helps.
In Safe Mode, only essential Windows processes run, which prevents other programs from interfering with repairs.
When to Use Safe Mode:
- SFC shows errors
- DISM repairs succeeded but Windows still behaves strangely
- You suspect a third-party driver or antivirus interference
How to Boot into Safe Mode:
- Open Settings
- Go to System → Recovery
- Under “Advanced startup,” click Restart now
- When the menu appears, choose Troubleshoot
- Go to Advanced options
- Select Startup Settings
- Click Restart
- Press 4 (Enable Safe Mode)
Once in Safe Mode, open Command Prompt as administrator and run:
sfc /scannow
This usually resolves stubborn issues.
8. What Issues Can DISM & SFC Fix?
Before concluding, let’s take a moment to appreciate what these tools can actually fix. Many users underestimate how powerful they are.
These tools can repair:
- Damaged Windows Update components
- Corrupted system files
- Missing DLL files
- Unstable Windows components
- Broken Start Menu or search
- Explorer crashes
- Blue screen errors caused by missing files
- Problems after failed updates
- System image corruption
- Performance issues due to system file damage
These commands cannot fix:
- Hardware problems
- Driver conflicts
- Malware issues
- Third-party app corruption
- Damaged user profile (in some cases)
Now let’s answer some common questions.
9. Frequently Asked Questions (Q&A)
Q1: How often should I run DISM and SFC?
Only when necessary — such as system instability, errors, or slow performance. Running them monthly is not required.
Q2: Do these commands delete my personal files?
No.
They only repair system components and do NOT touch your personal data.
Q3: Does SFC work without running DISM first?
Sometimes, but not always.
If your system image is corrupted, SFC won’t work properly — that’s why DISM should be used first.
Q4: Will this repair Windows without reinstalling it?
Yes.
This method repairs Windows at the system level and avoids a full reinstall.
Q5: Why does DISM require an internet connection?
Because it downloads healthy system files from Microsoft’s Windows Update servers.
Q6: What if both DISM and SFC fail?
You may need:
- A Windows repair upgrade
- Reset this PC
- Or deeper troubleshooting
But in 95% of cases, these commands fix the issue.
10. Final Thoughts
Repairing Windows doesn’t always require formatting your system or reinstalling everything from scratch. Tools like DISM and SFC exist exactly for this purpose — to restore stability without affecting your personal files.
By following the steps in this article, you can fix most types of corrupted system files, boot problems, update issues, slow performance, and other unexplained errors in Windows 11.
These tools take time, but they are incredibly effective. And once you repair your system image and core files, your computer often feels noticeably smoother and more stable.
If this article helped you or if you have any questions, feel free to share them in the comments. Troubleshooting Windows can feel overwhelming, but once you understand these tools, you gain a lot more control over your system’s health.
Take care — and may your Windows installation stay error-free.
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