Windows 10 Partition Layout
BIOS/MBR: https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/configure-biosmbr-based-hard-drive-partitions
1: SYSTEM - 100MB NTFS
2: Windows - Main Partition - 20GB+
3: Recovery - 300MB+ (I recommend 550MB)

UEFI/GPT: https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/configure-uefigpt-based-hard-drive-partitions
1: SYSTEM - 100MB+ FAT32
2: MSR - 16MB Microsoft reserved partition
3: Windows - Main Partition - 20GB+
4: Recovery - 300MB+ (I recommend 550MB)

Run the following from a command prompt (run from Recovery or Win10 Install media)

bootrec /scanos
bootrec /rebuildbcd
bootrec /fixmbr
bootrec /fixboot

To rebuild the EFI partition on a UEFI install, do the following. Please note that you need to verify the partition number you are deleting to verify it doesn't have important data.
diskpart
select disk 0 /////This should be your Windows drive
list par /////This will list all partitions on this drive. On the next line, select the EFI partition which is under 1GB in size
select partition 1 /////This should be the EFI partition, likely around 260MB in size
delete partition override
create partition EFI
for fs=FAT32 quick
assign letter=T
exit
bcdboot C:\Windows /s T: /f ALL
exit



If you get an Access Denied error and the drive is using UEFI (GPT partitions), follow these instructions
https://notes.airinscomputers.com/?item=13

If you get an Access Denied error and the drive is using MBR (BIOS partitions), follow these instructions.
Note, these don't really fix for all, but the commands may be useful in some instances.
https://www.tenforums.com/bsod-crashes-debugging/123444-bsod-inaccessible-boot-device.html
1) bcdedit /enum
2) bcdedit | find "osdevice"
3) diskpart
list disk
list volume
select disk 0 (pick your internal boot drive, likely 100GB+)
detail disk
list partition
select partition (pick 100MB partition)
format quick fs=ntfs label="System"
assign letter=s
exit
4) chkdsk /r /v C:
5) bcdboot C:\Windows /s S: /f ALL (if your Main boot drive is not C: then change this to the right letter)
6) dism /image:C:\ /cleanup-image /revertpendingactions
7) dism /Image:C:\ /Get-Packages
8) sfc /scannow /offbootdir=C:\ /offwindir=C:\windows
9) bootrec /fixmbr
10) bootrec /fixboot
11) bootrec /scanos
12) bootrec /rebuildbcd