Windows won’t boot…
So you have f’d up your Windows boot (EFI) partition or something.
Don’t panic! It can usually be rescued.
EFI partition deleted or otherwise gone?
Create/recreate EFI and MSR partition:
DiskPart
list disk
select disk <number of the disk shown by list>
list partition
select partition <number of EFI partition>
delete partition override
list partition
select partition <number of MSR partition>
delete partition override
create partition efi size=600
create partition msr size=16
list partition
select partition <number of EFI partition>
format quick fs=fat32 label="System"
assign letter=G
list vol
select vol <number of Windows volume>
assign letter=C
exit
Setup EFI to boot windows (asumes EFI mounted on G: and Windows on C:):
mkdir G:\EFI\Microsoft\Boot
xcopy /s C:\Windows\Boot\EFI\*.* G:\EFI\Microsoft\Boot
g:
cd EFI\Microsoft\Boot
bcdedit /createstore BCD
bcdedit /store BCD /create {bootmgr} /d “Windows Boot Manager”
bcdedit /store BCD /create /d “My Windows 10” /application osloader
The above command produces a GUID that should be used below in {your_guid}.
bcdedit /store BCD /set {bootmgr} default {your_guid}
bcdedit /store BCD /set {bootmgr} path \EFI\Microsoft\Boot\bootmgfw.efi
bcdedit /store BCD /set {bootmgr} displayorder {default}
bcdedit /store BCD /set {default} device partition=c:
bcdedit /store BCD /set {default} osdevice partition=c:
bcdedit /store BCD /set {default} path \Windows\System32\winload.efi
bcdedit /store BCD /set {default} systemroot \Windows
exit