I understand better now... It can be done, and grub can be repaired as
several have stated, but it's easier to install Windows first and then
Ubuntu will recognize it and create a grub which gives the choice of
O/S's automatically. In other words, Ubuntu is Windows aware and
friendly, but Windows ignores any other O/S and won't let you boot to
anything but Windows without taking special steps. That can be done
fairly easily and successfully, but it's a nuisance!