A nice story of strength...
Silent, I can't wait here silent
 Working up a storm inside my head
 Nothing, I just stood for nothing
 So I fell for everything you said
 
 Hear the rumble
 Hear my voice
 
 Silent, I can't wait here silent
 Gotta make a change and make some noise
 
 Undo my sad
 Undo what hurts so bad
 Undo my pain
 Gonna get out, through the rain
 I know that I am over you
 At last I know what I should do
 Undo my sad
 
 Trouble, baby I'm in trouble
 Everytime I look into your eyes
 Save me, oh I'm gonna save me
 Far away from all the crazy lies
 
 Hear the rumble
 Hear my voice
 
 Undo my sad
 Undo what hurts so bad
 Undo my pain
 Gonna get out, through the rain
 I know that I am over you
 At last I know what I should do
 Undo my sad
 Undo my sad
 Undo what hurts so bad
 Undo my pain
 Gonna get out, through the rain
 I know that I am over you
 At last I know what I should do
 Undo my sad
 My sad love undo
SILENT= Without sound.
WORKING UP= To develop or produce by mental or physical effort; in this case a storm inside her head.
RUMBLE= A deep resonant sound.
GOTTA= (Informal) Contraction of '(have) got to' = must.
MAKE A CHANGE= To grow or become better by reforming oneself.
MAKE SOME NOISE= To attract attention. To do something noticeable.
UNDO= Lead to downfall, destroy.
MY SAD= This doesn't make any sense, because SAD is an adjective and here it is used with a possessive adjective, like a noun. In fact we here "my sad" many times through the song without knowing what is the sad thing she is talking about, because every time she's going to say it, the sentence stops. It is only at the end, the last line, when we hear the complete sentence: MY SAD LOVE.
PAIN= Suffering.
GET OUT= To leave or escape.
I AM OVER YOU= I've moved on (if used at the end of a relationship). It means that at one time I had feelings for you , but now those feelings are gone and now I am indifferent to them or at least not trapped by them.
AT LAST= Finally.
I'M IN TROUBLE= I'm in difficulty, in affliction.
FAR AWAY FROM= At a distance.
Sanna explains that 'Undo' is about many things. It is up to the listener to decide what exactly it means to them. The first thing you think about is that it is about a relationship that is not very good and you really want to be in a better place, but I think it is important to know that there still is hope. It is not bad all the time. You have the strength to do something about it.