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Fix Windows that has dual boot that will not work

We'll fix the boot loader, repair Windows Boot Manager, and restore the menu—or tell you when to call a pro.

Troubleshooting · Home maintenance
30–90 min
What you'll need
  • Windows install USB (for Recovery)
  • Linux live USB (for GRUB repair)
Step 1 of 5

Quick triage — pick your path

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Choose the option that matches what you see. You can jump straight to that section.

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Steps

Goal: Fix the boot loader and restore the dual-boot menu.

  • Check boot order—set Windows Boot Manager or the dual-boot loader first.
  • Good: Boot menu appears or one OS loads. Proceed to repair.
  • Bad: Use Windows Recovery or Linux live USB.

Check boot order

Goal: Set the correct boot loader first in BIOS.

  • Enter BIOS, set “Windows Boot Manager” or the disk with the boot loader first. Save and exit.
  • Good: Boot menu appears on restart.
  • Bad: Use Recovery to repair BCD.

Repair BCD

Goal: Restore Windows Boot Manager.

  • Boot to Recovery (Shift + Restart or install USB). Command Prompt: bootrec /fixmbr, bootrec /fixboot, bootrec /scanos, bootrec /rebuildbcd.
  • Good: Boot menu shows Windows. If Linux is missing, reinstall GRUB from Linux live USB.
  • Bad: Reinstall GRUB from Linux live USB.

Reinstall GRUB

Goal: Restore the Linux boot loader.

  • Boot Linux live USB. Mount the Linux root partition. Run grub-install and update-grub. Or use Boot-Repair.
  • Good: GRUB appears with both OSes.
  • Bad: Call a technician.

When to get help

Call a technician if:

  • bootrec and GRUB reinstall fail.
  • Partitions are corrupted.
  • You need data recovery.

Verification

  • Boot menu appears on startup.
  • Both Windows and Linux are listed.
  • Each OS boots when selected.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Boot order Set Windows Boot Manager or dual-boot loader first.
  2. Repair BCD Run bootrec from Windows Recovery.
  3. Reinstall GRUB Boot Linux live USB; grub-install and update-grub.
  4. Call a pro Repairs fail or partitions corrupted.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Boot order in BIOS
  • Whether Windows or Linux loads alone
  • Error message (GRUB, BCD, etc.)
  • Steps already tried

Does any OS boot?

If Windows boots, use Recovery. If Linux boots, use live USB.

Check boot order in BIOS. Set Windows Boot Manager first. Good: boot menu or one OS loads—proceed to repair. Bad: try Recovery or Linux live USB.

Yes No

You can change your answer later.

Which OS loads?

If Windows loads: use Recovery, run bootrec. If Linux loads: use live USB, reinstall GRUB. If neither: use Recovery first, then Linux live USB.

Windows Linux

You can change your answer later.

Repair BCD from Recovery

Hold Shift + Restart. Troubleshoot → Advanced options → Command Prompt. Run bootrec /fixmbr, bootrec /fixboot, bootrec /scanos, bootrec /rebuildbcd. Restart. If GRUB still missing, reinstall from Linux live USB.

Done

Reinstall GRUB from live USB

Boot Linux live USB. Mount root partition. Run grub-install and update-grub. Or use Boot-Repair. Restart. If still fails, run bootrec from Windows Recovery.

Done

Use Recovery or Linux live USB

Try Windows install USB first—Repair your computer, run bootrec. If that fails, try Linux live USB and Boot-Repair. If neither works, call a technician.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would dual boot not work?
Windows update overwrote GRUB, wrong boot order, corrupted BCD, or failed boot loader. Check boot order and repair BCD or GRUB.
Can I fix dual boot myself?
Yes. Repair Windows Boot Manager with bootrec, or reinstall GRUB from a Linux live USB. Set correct boot order in BIOS.
When should I call a technician for dual boot?
If bootrec and GRUB reinstall fail, or you need to recover data from a partition. Complex partition layouts may need a professional.

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