How do I update Grub2 when I can't boot into linux at all?

[James R McKenzie]

I tried to install KDE 4.10.? (what ever the latest version is) Ubuntu 13.04 64 bit and can't boot into it at all. The short answer as to why I want KDE is I detest Mate, Cinnamon and all the other Gnome 3 desktops. How do I remove it (Ubuntu 13.04) from GRUB2 and boot Linux Mint 14 by default. I tried to download & install Grub Doctor but came up with dependency issues, ie it won't install.

If you can help please do.

Thank You

James R McKenzie

jimmckenzie at earthlink.net