Dual Boot problem

[farxok]

My Problem with Ubuntu and Windows

I am experiencing an issue with my dual-boot system. I have a Lenovo laptop with one hard drive, divided into two partitions: one for Windows and one for Ubuntu.

After updating or reinstalling Ubuntu, the system only boots directly into Ubuntu. The GRUB bootloader does not show the option to start Windows, and I cannot access my Windows programs or files from the boot menu.

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Possible Causes

1. GRUB was reinstalled incorrectly – it only points to Ubuntu and does not list Windows.

2. Windows Fast Startup / Hibernation – if Windows was hibernating, Ubuntu cannot properly detect or mount the Windows partition.

3. Different boot modes – Windows might have been installed in UEFI mode, while Ubuntu was installed or reinstalled in Legacy mode. When the boot modes do not match, GRUB cannot find Windows.

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Possible Solutions

1. Update GRUB from Ubuntu
   Run in the terminal:

sudo update-grub

This command scans the system for other operating systems and adds Windows to the GRUB menu if detected.

2. Check the BIOS/UEFI Boot Mode

If Windows was installed in UEFI, the BIOS must be set to UEFI.

If Windows was installed in Legacy, the BIOS must be set to Legacy.
Both systems must use the same mode.

3. Disable Windows Fast Startup
   This can only be done inside Windows. If I cannot boot Windows, I may need a recovery tool first.

4. Use a Windows Recovery USB (last resort)
   Boot from a Windows installation USB, select Repair your computer → Startup Repair.
   This will restore the Windows boot loader. Later, GRUB can be reinstalled if I still want dual-boot.

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Conclusion

Windows is still on the disk, but GRUB does not show it. To fix this, I need to:

Ensure Ubuntu and Windows use the same boot mode (UEFI or Legacy).

Update or reinstall GRUB to detect Windows.

If necessary, use a Windows recovery USB to repair Windows boot.

I don’t know what to do.

[wgarcia]

Welcome to Ubuntu Discourse! I’ve moved your post to its own thread, as you reused an old thread (we call it necroposting), and your problem may be different from that thread.

[oldfred]

If you need more help that the details you posted on fixes, we need to see details on your configuration.

Please copy & paste the pastebin link to the BootInfo summary report ( do not post report), do not run the auto fix till reviewed. Use ppa (2nd) with live installer or update Boot-Repair ISO when booted.
Boot-Repair - Community Help Wiki &
https://sourceforge.net/p/boot-repair/home/Home/