Not done.
To reverse the effects of an action.
Fortunately, we can undo most of the damage to the system by the war.
To unfasten.
Could you undo my buckle for me?
To impoverish or ruin, as in reputation; to cause the downfall of.
Not fastened.
Your flies are undone.
Ruined; brought to nought.
Woe is me, for I am utterly undone!