This assumes you were setup for Windows / Linux dual booting until some major event ocurred. You’re sure your Windows installation is in perfect condition, it’s just that grub will not find your Redmon OS.
Follow along for a quick-and-dirty howto to repair your bootloader!
Phase 1: SetUp
- Make sure your Windows installation is really there
- Install VirtualBox on your Linux OS
- Create a Windows VM without adding any HD’s
- Configure UEFI in the new VM [1]
- Create virtual HD’s for both your Windows installation and the one containing the UEFI partition [2]
- Attach these HD’s to your new VM, as well as your Windows 10 media [3]
Phase 2: Recovering your Windows UEFI Bootloader
- Start the VM, choose the repair option when prompted, then command prompt
- Follow this tutorial, skipping the “set id” command in Step 3 [4]
Phase 3: Update your GRUB
- Reboot into your bare-metal Linux install
- Install “os-prober”, just in case
- Update your grub setup with “sudo update-grub” (if your distro command is different, leave a note and I’ll gladly update this howto!). For this step to work, it is important that the UEFI partition is mounted (on my setup it’s mounted at /boot/efi).
- Reboot (Windows should be available now)
Links
[1] https://www.serverwatch.com/server-tutorials/enabling-uefi-on-virtual-machines.html
[2] https://www.serverwatch.com/server-tutorials/using-a-physical-hard-drive-with-a-virtualbox-vm.html
[3] https://www.microsoft.com/pt-br/software-download/windows10
[4] https://www.easeus.com/partition-manager-software/fix-uefi-boot-in-windows-10-8-7.html
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