Did you just get a Windows boot failure
- on an EFI boot machine
- missing file
- error code
- when you are running native (boot from VHD, VHDX)
- and just deleted a differencing disk
- but did not first delete the BCD entry that referred to the differencing disk?
If so … boot from a Windows setup USB stick/DVD/whatever, and use BCDEDIT to delete the boot entry that still refers to the differencing disk. Then you’re good to go.
Apparently with a sufficiently bad entry in the BCD store you get a nasty catastrophic failure and don’t even get a choice to boot from one of the other installed operating systems. But don’t succumb to a heart attack. Correct it by booting from a different device (setting the BIOS boot order if necessary) and deleting the bad entry in the BCD.
(By the way, this superuser/stackoverflow page would have been a real help fixing more “normal” EFI boot problems if I hadn’t borked my machine in a particularly stupid way.)