Just to confirm, this is not a new install but wanted to remove an empty old HDD from the system but couldn't boot without it despite it not being the windows install disk. Anyway, past that, as won't boot either way.
So this is what I have just done;
Installed Hirens BootCD PE Windows 10 and put onto USB
Went to the command prompt
used bootrec.exe /ScanOs to check windows install, confirmed on D:\
put in bcdboot d:\windows /s d: - Boot files successfully created. Shutdown and remove usb.
Restart and then exactly the same error message - dammit.
Any other suggestions?