Broken File Associations

OK, I’ve been stupid.
Somehow I’ve managed to remove the File Association for “Shortcut” and now none of the links in my start menu, or the Office Shortcut Bar will work.
Does anyone have any idea of how I reinstate this (short of re-installing Windows).

Microsoft’s site isn’t much help (unless I’m asking the wrong questions) and I can’t find too much out on the web other than generic tutorials on creating/assigning file associations (Shortcut seems to be special case).