How are you booting your OS's if Grub can't find them?
Google gets a lot of hits for "remove Grub". I can't speak for any of them. You may want to just reinstall Grub (or configure it correctly, depending on how badly Windows screwed it up) and use it to decide between Windows and Linux.
Ubuntu Server does not have a GUI. Most enterprise-level servers run headless, that is, without a window system. Without an interactive user, a GUI would just take up valuable resources. If you want a GUI, you can install one.
Here is one way.