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 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
This site is meant to be used as a reference for myself, although others may find it useful. I use it to keep track of certain fixes, software, and other solutions which I may need while assisting customers. The page layout is pure HTML/CSS and is kept simple to optimize loading time and fast results.