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How to Fix Lost Windows 10 After Installing Ubuntu: Step-by-Step Solution

If you have installed Ubuntu alongside Windows 10 and suddenly can’t find or boot into Windows, you are not alone. This issue happens because the Ubuntu installation sometimes overwrites the Windows bootloader. Don’t worry—it can be fixed with a few simple steps.

This guide will walk you through how to restore access to your Windows 10 installation after installing Ubuntu. We will start with the easiest solutions and move to more advanced ones if needed.

By following these instructions carefully, you should be able to choose between Ubuntu and Windows again at startup. Let’s get started.

Make sure you follow every step thoroughly to avoid causing more boot issues.

Quick Note: Prerequisites and Important Checks

Before you begin, here are a few things to check and prepare:

  • Backup Important Data: If possible, back up any important files from both Windows and Ubuntu to an external drive. This is just a precaution.
  • Access to Ubuntu: Ensure you can boot into Ubuntu since most fixes require using Ubuntu’s tools.
  • Internet Connection: A working internet connection is helpful for downloading any necessary software or updates.
  • Windows Recovery Media: Having a Windows 10 installation USB or recovery disk is useful if the bootloader repair doesn’t work.

Step 1: Update GRUB Bootloader in Ubuntu

The most common reason Windows 10 disappears from the boot menu is that the GRUB bootloader (used by Ubuntu) doesn’t detect Windows automatically. Updating GRUB often fixes this.

  1. Start your computer and boot into Ubuntu.
  2. Open the Terminal. You can do this by pressing Ctrl + Alt + T.
  3. Type the following command and press Enter:
sudo update-grub

This command makes Ubuntu search for all operating systems, including Windows, and updates the boot menu accordingly.

After it finishes, reboot your computer and check if Windows 10 appears in the boot menu.

Step 2: Use Boot Repair Tool in Ubuntu

If updating GRUB does not work, you can use a tool called Boot Repair. It automatically fixes many boot problems.

  1. Boot into Ubuntu.
  2. Open Terminal.
  3. Run these commands one by one to install Boot Repair:
sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt update
sudo apt install -y boot-repair

After installation, launch Boot Repair by typing:

boot-repair

The Boot Repair window will open. Click on Recommended repair. This will scan your system and fix bootloader issues.

When done, reboot your computer and check if Windows 10 appears in the boot menu.

Step 3: Repair Windows Bootloader Using Windows Installation Media

If the above steps don’t restore Windows, the Windows bootloader itself may be damaged. You can repair it using Windows 10 installation media.

  1. Insert your Windows 10 USB or DVD and boot from it. To do this, you might need to press a key like F12 or Esc during startup to choose the boot device.
  2. Once in the Windows setup screen, click Next, then select Repair your computer at the bottom left.
  3. Go to Troubleshoot > Advanced options > Command Prompt.
  4. In Command Prompt, type these commands one by one, pressing Enter after each:
bootrec /fixmbr
bootrec /fixboot
bootrec /scanos
bootrec /rebuildbcd

These commands rewrite the Windows bootloader and update the boot configuration.

Type exit and press Enter to close Command Prompt. Restart your PC.

At this point, Windows should boot normally, but Ubuntu may not appear in the boot menu anymore. You can restore the GRUB bootloader later if you want to dual boot again.

Step 4: Reinstall GRUB to Enable Dual Boot Again (Optional)

If you want to have both Ubuntu and Windows available at startup, after repairing Windows bootloader, you need to reinstall GRUB.

  1. Boot into Ubuntu live USB (the installation media).
  2. Open Terminal.
  3. Find your Ubuntu root partition by running:
    4. sudo fdisk -l

    Look for the partition labeled Linux filesystem, e.g., /dev/sda5.

  4. Mount the partition:
    5. sudo mount /dev/sda5 /mnt
  5. Reinstall GRUB on the disk (replace /dev/sda with your disk):
    6. sudo grub-install --boot-directory=/mnt/boot /dev/sda
  6. Update GRUB:
    7. sudo chroot /mnt
update-grub
exit
  7. Reboot your computer. You should see both Ubuntu and Windows in the boot menu.

Alternative Method: Use EasyBCD in Windows

If you can boot into Windows but want to manage the boot menu more easily, you can use a tool called EasyBCD.

  • Download EasyBCD from its official website.
  • Install and run EasyBCD.
  • Use its features to add Ubuntu to the Windows bootloader menu.

This method is helpful if you prefer the Windows boot menu over GRUB.

FAQs

Why did I lose access to Windows 10 after installing Ubuntu?

Ubuntu’s installer often replaces the Windows bootloader with GRUB. Sometimes GRUB does not detect Windows correctly, causing it to be missing from the boot menu.

Can I fix the bootloader without reinstalling Ubuntu?

Yes. Updating GRUB or using Boot Repair can fix the bootloader without reinstalling Ubuntu.

Will repairing the Windows bootloader remove Ubuntu?

Repairing the Windows bootloader may remove GRUB, which prevents Ubuntu from booting. You will need to reinstall GRUB to restore dual boot.

Is it safe to use Boot Repair?

Yes, Boot Repair is a widely used tool designed to fix bootloader problems safely.

What if I don’t have Windows installation media?

You can create a Windows 10 installation USB using Microsoft’s Media Creation Tool on another Windows PC.

When Nothing Works

If none of the above solutions work, consider these last resorts:

  • Use official Microsoft recovery tools or contact Microsoft support for Windows repair.
  • Reinstall Windows 10 and Ubuntu carefully, making sure to set up dual boot properly.
  • Visit Ubuntu and Windows forums for help from the community.

Links to official resources:

Conclusion

Losing access to Windows 10 after installing Ubuntu can be frustrating, but it is usually fixable. Start by updating the GRUB bootloader, then try the Boot Repair tool if needed. If that doesn’t work, repairing the Windows bootloader using installation media is the next step.

Remember to back up your data before making changes and follow each step carefully. With patience and these solutions, you can restore your dual boot system and enjoy both operating systems once again.

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