SOLVED: Windows 10 won’t boot after Ubuntu install

Use diskpart

• Make a Bootable USB of Windows 10 or a DVD by using any USB Creation Tool Like Rufus.

• Reboot your Device (PC/Laptop) and you need to go in “Advanced options”.

• In the window "Advanced options” shows after the device boots from the USB or DVD, you will need to left click on “Troubleshoot”.

• After left clicking on “Troubleshoot”, select “Advanced Options” and then select “Command Prompt”.

• In the command prompt window type “diskpart” Hit “Enter” .

• Type the “sel disk 0” command and hit “Enter” .

• In the command prompt type “list vol” and hit “Enter” .

• The EFI partition you have there should be a “FAT32” partition.

Note: Depending on what volume your EFI partition is you will have to follow the next steps accordingly

• For example that the “EFI” partition is Volume 2.

• Now type in the command prompt sel vol 2”  and “Enter”.

• Now type in the command prompt  “assign letter=a”

• After you hit “Enter” , you will get a message saying 

“DisKPart successfully assigned the driver letter or mount point”.

• Type  “exit” and hit Enter in the command prompt.

• Now you will still have the command prompt window in front of you but you will be take out of the “DISKPART>” feature.

• Now type in the command prompt window “cd /d a:EFIMicrosoftBoot” and again “Enter”.
• Now Type “bootrec /fixboot” and again Enter.

Note: The bootrec /fixboot command will repair your selected drive.

• Now type in the command prompt “ren BCD BCD.old” and hit “Enter” from keyboard.
• Type in the command prompt “bcdboot c:Windows /l en-us /s a: /f ALL” and once again “Enter”.
• Now Remove Your Bootable USB or DVD and try a reboot of the system(PC/Laptop).