Booting from recovery media for repairs

What you see

Start with the screen. The exact error matters.

• BOOTMGR is missing
• INACCESSIBLE_BOOT_DEVICE
• 0xc000000f
• 0xc0000225
• Automatic Repair couldn’t repair your PC

Copy the error text or take a photo. A black screen after POST, an Automatic Repair loop, or a halt on the manufacturer logo all point in different directions. Persistent beeps, drives that spin up and stop, and SMART errors from firmware point more towards hardware trouble.

Write down how far the boot gets. I use notes like these:

• POST completes, then black screen, no cursor.
• Manufacturer logo, then Automatic Repair loop.
• Error on-screen: INACCESSIBLE_BOOT_DEVICE.

BitLocker prompts are part of the problem too. If a firmware change triggers a recovery key request, that is expected. Get the key from your normal recovery route rather than guessing at fixes.

Where it happens

Windows boot failure usually lands in one of a few places:

• Firmware hands off to the bootloader.
• The bootloader finds Windows Boot Manager and the BCD.
• The kernel and drivers load.
• Winlogon takes over and the user session starts.

That leaves a short list of usual suspects: firmware settings, corrupted Boot Configuration Data, missing boot files, driver or disk faults, BitLocker problems, and the wrong boot mode. Fast Startup and hybrid sleep can hide issues. If the machine uses PXE or network boot, bad firewall rules on the network can make it look dead when it is just failing to reach DHCP or TFTP.

The recovery media I use is plain enough:

• Official Windows installation USB for Startup Repair and Command Prompt.
• Windows PE for offline repair and imaging.
• A second working PC for making recovery media or checking error strings.

Firmware mode needs to match the install. UEFI and Legacy are not interchangeable. Secure Boot can block unsigned bootloaders. If the system used UEFI before and has been switched to Legacy, the bootloader will not be where Windows expects it.

Find the cause

Run the simple checks first and write down the output.

diskpart
list disk

The system disk should appear with the right size. No disk, or the wrong size, points to hardware or cabling.

bcdedit /v

Healthy output shows Windows Boot Loader entries and a path like Windowssystem32winload.exe. If the BCD store will not open, that is a useful clue on its own.

bootrec /scanos

This should list Windows installations. If it finds none, the BCD is likely damaged or the install is not being seen properly.

When Windows will not reach the desktop, use recovery media and check the logs from there. The System log and BootDiag events are the main ones to look at. If needed, inspect C:WindowsSystem32winevtLogsSystem.evtx on another machine, or export it with wevtutil.

Then check the hardware.

• SATA power and data cables are seated.
• NVMe modules are fully in their sockets.
• RAM is reseated and tested one stick at a time.
• The drive is not clicking or dropping out.

If the disk looks flaky, run chkdsk from recovery:

chkdsk C: /f /r

A healthy disk should not report bad sectors. If it does, treat the drive as suspect and move to replacement and backup recovery.

The common causes I see are corrupted BCD, missing boot files, disk faults, storage driver breakage, BitLocker key mismatches, and the wrong firmware mode.

Fix

Work through it in order. If there is a recent image backup, restore that first. If not, start with Startup Repair and move to manual fixes if that fails.

1. Run Startup Repair from recovery media.

   Repair your computer > Troubleshoot > Advanced options > Startup Repair

   If it fixes the boot issue, note what changed and make a system image straight away.

2. If Startup Repair fails, open Command Prompt and run:

   bootrec /fixmbr
   bootrec /fixboot
   bootrec /scanos
   bootrec /rebuildbcd

   If bootrec /fixboot returns Access is denied, work with the EFI partition:

   diskpart
   list vol
   select vol X
   assign letter=Z:
   exit
   bcdboot C:Windows /s Z: /f UEFI

   Only format the EFI partition if you know the layout is broken. Do not do it by default.

3. Repair system files:

   sfc /scannow

   If SFC will not run offline, use DISM instead:

   DISM /Image:C: /Cleanup-Image /RestoreHealth

4. Deal with BitLocker issues:

   • If BitLocker asks for a recovery key after a hardware change, use the key.
   • Suspend BitLocker before firmware or driver changes.

5. Check the system settings:

   • Disable Fast Startup in Control Panel while troubleshooting.
   • Make sure UEFI or Legacy in firmware matches the disk style, with GPT for UEFI and MBR for Legacy.
   • If a driver update caused the break, use System Restore or remove the driver from recovery.

If you replace hardware such as an NVMe drive, restore from an image. If there is no image, copy the raw data off with imaging tools from WinPE before you do anything else.

Check it’s fixed

Reboot it several times and write down the result. A proper fix reaches the sign-in screen every time, not just once.

• Run sfc /scannow and DISM /Online /Cleanup-Image /RestoreHealth from a full boot.
• Check Event Viewer for recent critical errors by filtering System for Kernel-Boot and Kernel-Power events.
• Check disk health and SMART. wmic diskdrive get status should return OK on a healthy drive.

Keep an eye on it for a week. If the same error comes back, record the exact string and the event timestamps. Useful logs to keep:

• C:WindowsSystem32winevtLogsSystem.evtx
• Windows btlog.txt, which you can create with boot logging enabled through msconfig or bcdedit /set {current} bootlog yes

A simple backup pattern saves a lot of grief later. I use a weekly image backup and a daily file-level sync. I also create restore points before major updates. If the machine relies on network booting, keep the PXE firewall rules written down and test them after changes.