To repair a Windows 10 or Windows 11 PC that will not boot, open the Windows Recovery Environment, run Startup Repair, try Safe Mode, and rebuild the boot records with bootrec if the first two fail.
This guide gives the exact menu paths and commands for each stage, what each one fixes, and what to do when bootrec /fixboot returns Access is denied.
Repair Windows 10/11 boot problems with Startup Repair, Safe Mode, and bootrec
- Open WinRE: hold Shift while you select Power > Restart, or let Windows open it after two failed starts.
- Select Troubleshoot > Advanced options > Startup Repair.
- Restart and test. If Windows still fails, start Safe Mode and remove the recent update, driver or app.
- If the PC still will not start, open Command Prompt in WinRE and run
bootrec /fixmbr,bootrec /fixboot,bootrec /scanosandbootrec /rebuildbcd. - Restart the PC and check that Windows reaches the sign-in screen.
Prerequisites
| What you need | Why |
|---|---|
| Windows installation media or a recovery drive for the same Windows version | Opens WinRE when the PC cannot reach it on its own |
| Your BitLocker recovery key | WinRE may ask for it before it unlocks the system drive |
| An administrator account password | Some recovery tools ask you to sign in |
| About 30 to 60 minutes | Startup Repair and scans can take a while |
| Disconnected external peripherals | Rules out a USB device or drive blocking startup |
Step 1: Enter the Windows Recovery Environment (WinRE)
WinRE opens on its own after two failed attempts to start Windows, two unexpected shutdowns within two minutes of boot completing, two reboots within two minutes of boot completing, or a Secure Boot error.
| Situation | How to open WinRE |
|---|---|
| If the PC still partially boots (sign-in screen loads) | Select Power, hold Shift and select Restart |
| You can sign in | Open Settings > Recovery and select Restart now next to Advanced startup |
| If the PC does not reach recovery automatically | Boot from installation media, then select Next > Repair your computer |
| OEM device with a recovery button | Use the hardware recovery button or key combination the maker configured |
Each route ends on Choose an option. Select Troubleshoot > Advanced options to reach every tool in this guide.
Step 2: Run startup repair
- On Choose an option, select Troubleshoot.
- Select Advanced options > Startup Repair.
- Pick your account and enter its password if asked.
- Wait while the tool analyses startup logs and applies repairs.
- Select Shutdown, then turn the PC on to see whether Windows starts.
What Startup Repair can fix
Startup Repair diagnoses the boot by reading startup log files and any crash dump, then repairs the cause it finds.
| Problem | Startup Repair helps? |
|---|---|
| Corrupted or missing operating system or driver files named in the boot logs | Yes |
| Boot configuration and boot file errors | Often; bootrec covers what it misses |
| A faulty update, driver or app that loads after Windows starts | Rarely; use Safe Mode |
| Failed hardware or a disk the firmware cannot detect | No |
What to do after it finishes
- Restart the PC and watch whether Windows reaches the sign-in screen.
- If it does, sign in and open
%windir%\System32\LogFiles\Srt\SrtTrail.txtto read what was found and repaired. - If the log names a driver or file, update or remove that item.
- If Windows still fails, run Startup Repair again before moving to Safe Mode.
Step 3: Try safe mode
Safe Mode loads a minimal set of drivers and services. Microsoft documents a command that brings back the F8 Advanced Boot Options menu, which lists Safe Mode and Safe Mode with Networking.
- In WinRE, select Troubleshoot > Advanced options > Command Prompt.
- Run
bcdedit /set {default} bootmenupolicy legacyand close the window. - Select Continue or restart the PC, and press F8 while it starts.
- Choose Safe Mode or Safe Mode with Networking from the menu.
- When the repair is finished, run
bcdedit /set {default} bootmenupolicy standardto restore the normal boot menu.
If Windows still opens, you can also enable the F8 key for Safe Mode ahead of time so the menu is ready next time.
Once in Safe Mode, check the following:
| Check | What to look for |
|---|---|
| Event Viewer > System log | Errors logged at the time the boot failed |
| Recently installed updates | An update installed just before the problem began |
| Recently added drivers or apps | Anything new since the last good start |
Services in System Configuration (msconfig) |
Use Selective startup to test services one at a time; the culprit is usually third-party |
Uninstall a recent update
When Windows will not start at all after an update, remove the pending package from the WinRE Command Prompt. Replace C: if Windows sits on another letter in WinRE.
- Open Command Prompt from Troubleshoot > Advanced options.
- Run
DISM /image:C:\ /get-packagesand note any package marked as pending. - Run
DISM /image:C:\ /remove-package /packagename:<package name>for that package. - Run
DISM /Image:C:\ /Cleanup-Image /RevertPendingActions. - Restart the PC and test.
Remove a newly installed driver or app
- In Safe Mode, right-click Start and select Device Manager.
- Right-click the device whose driver you added and select Uninstall device.
- For an app, open Settings > Apps > Installed apps, select the three dots beside it and choose Uninstall.
- Open
msconfig, select Selective startup on the General tab, and test third-party services if the cause is unclear. - Switch back to Normal startup and restart.
Run system file checker
In Safe Mode, run sfc /scannow from an administrator Command Prompt. From WinRE, point SFC at the offline Windows folder instead.
sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows/scannow checks every protected system file and repairs damaged ones when possible. /offbootdir and /offwindir tell SFC where the offline boot folder and Windows folder are when you run it from WinRE.
You should see: SFC reports that it found no integrity violations, or that it found corrupt files and repaired them.
Step 4: Use bootrec to repair boot records
Use bootrec when the screen is black with a blinking cursor, or you see BCD missing or corrupted, Bootmgr missing, Operating system missing, or Boot sector missing.
- Open Command Prompt in WinRE, or press Shift + F10 on the installation media setup screen.
- Run
bootrec /fixmbr. - Run
bootrec /fixboot. - Run
bootrec /scanosto list the Windows installations it can find. - Restart and test. If BCD errors remain, continue with the rebuild below.
What each command does
| Command | What it does |
|---|---|
bootrec /fixmbr |
Rewrites the master boot code; it does not repair a damaged partition table |
bootrec /fixboot |
Repairs the boot sector |
bootrec /scanos |
Scans all disks for Windows installations |
bootrec /rebuildbcd |
Rebuilds the Boot Configuration Data store from the installations it finds |
bcdboot C:\Windows |
Copies fresh boot files to the system partition and creates a boot entry |
If Windows installation is found
If bootrec /scanos lists your Windows installation but the BCD still fails, back up and rename the old store, then rebuild it.
- Run
bcdedit /export c:\bcdbackupto save the current store. - Run
attrib c:\boot\bcd -r -s -hto make the file editable. - Run
ren c:\boot\bcd bcd.old. - Run
bootrec /rebuildbcdand press Y to add the installation it finds to the boot list. - Restart the PC.
Step 5: If “Access is denied” appears with bootrec /fixboot
On many UEFI PCs, fixboot cannot write to the EFI system partition. BCDBoot rebuilds the boot files there instead, and on UEFI it also adds a Windows Boot Manager entry to the firmware.
- Stay in the WinRE Command Prompt.
- Run
bcdboot C:\Windows, replacingC:with the Windows drive letter shown bybootrec /scanos. - If the system partition has a letter, such as S:, target it with
bcdboot C:\Windows /s S: /f UEFI. - Wait for the message that boot files were created successfully.
- Restart the PC.
Step 6: Restart and test
- Remove the installation media so the PC boots from its own drive.
- Restart and confirm Windows reaches the sign-in screen.
- If WinRE keeps reopening in a loop, run
bcdedit /set {default} recoveryenabled nofrom its Command Prompt to break the cycle, then turn it back on withrecoveryenabled yesonce Windows boots. - Sign in and check Event Viewer for new errors.
Tips and troubleshooting notes
| Tip | Why it matters |
|---|---|
| 1. Know whether your system uses UEFI or Legacy BIOS | UEFI PCs boot \EFI\Microsoft\Boot\bootmgfw.efi, BIOS PCs use the MBR and bootmgr, so the right fix differs; the firmware boot menu lists entries such as UEFI: USB Drive or BIOS: USB Drive |
| 2. BitLocker may prompt for a recovery key | WinRE asks for the key before it unlocks an encrypted drive; a Microsoft account stores it for personal devices |
| 3. Startup Repair may need more than one pass | Run it again after each restart until it reports no new fixes |
| 4. Use Safe Mode for software-related failures | Stop errors after the logo, black screens and spinning dots usually point to a driver, update or service |
| 5. Keep a recovery USB ready | Installation media opens WinRE when the internal recovery partition is damaged |
Windows 10/11 still won't boot after bootrec
No disk light and NumLock does not toggle
The PC is stuck in the firmware (BIOS) phase, which points to hardware.
- Disconnect every external peripheral.
- Check that the firmware detects the system disk.
- Contact the PC maker if the disk is not listed.
INACCESSIBLE_BOOT_DEVICE (Stop 0x7B)
A storage driver or filter driver fails to load the boot disk.
- Undo any recent change to the disk controller (SATA) mode in firmware.
- Remove recent updates with the DISM commands above.
- Use a System Restore point from Advanced options > System Restore.
bootrec /scanos finds zero Windows installations
The Windows partition is unreadable, locked by BitLocker, or on a different letter in WinRE.
- Enter the BitLocker recovery key if WinRE requests it.
- Run
bcdbootwith the correct Windows drive letter. - Restore from a backup or reset the PC if the partition cannot be read.
Windows boot repair FAQ
How do I get to Startup Repair if Windows won't boot?
Windows opens the recovery environment by itself after two failed starts. Otherwise boot from Windows installation media, select Next > Repair your computer, then Troubleshoot > Advanced options > Startup Repair.
Does bootrec delete files?
No. bootrec rewrites boot code, the boot sector and the Boot Configuration Data, not personal files. bootrec /fixmbr only overwrites the master boot code, so it will not repair a damaged partition table.
Why does bootrec /fixboot say Access is denied?
It usually happens on UEFI PCs where fixboot cannot write to the EFI system partition. Run bcdboot C:\Windows with the correct Windows drive letter to recreate the boot files there instead.
Where is the Startup Repair log file?
Startup Repair writes its log to %windir%\System32\LogFiles\Srt\SrtTrail.txt. It records what the tool diagnosed and which repairs it applied, which helps when the same failure returns.
How do I stop an automatic repair loop?
Open Command Prompt in WinRE and run bcdedit /set {default} recoveryenabled no to break the cycle. Fix the underlying cause, then turn recovery back on with recoveryenabled yes.
Can I run SFC from the recovery environment?
Yes. Use the offline switches, for example sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows, replacing C: with the drive that holds Windows in WinRE.
Why does Windows ask for a BitLocker recovery key in WinRE?
WinRE needs the key to unlock an encrypted system drive before Startup Repair or command-line tools can read it. Personal devices signed in with a Microsoft account usually store the key in that account.
Startup Repair or bootrec: which fix first?
Run Startup Repair first, use Safe Mode when Windows fails after the logo, and save bootrec and bcdboot for boot-loader errors such as BCD missing or a black screen with a cursor. Startup Repair reads the boot logs and fixes the specific file it finds, while bootrec rewrites boot structures and only helps when those are the damaged part.
