this is not how demi lovato plays it but the chords do fit the song. enjoy =) sry for 
mistakes in the lyrics..

D
Did you forget
           G
That I was even alive
        A
Did you forget
F
Everything we ever had
        D
Did you forget
        G
Did you forget
      D
About me
D
Did you regret
      G
Ever standing by my side
        A
Did you forget
F
What we were feeling inside
        D
No more left
G
To forget
D
About us

(CHORUS)
F       C             G
But somewhere we went wrong
F       C       G
We were once so strong
F           C      G
Our love is like a song
F               D
You cant forget it

D
But now I guess
G
This is where we have to stand
A
Did you regret
     F
Ever holding my hand
D
Never again
G
Please don't forget
D
Don't forget
D
We had it all
G
We were just about to fall
A
Even more in love
F
Than we were before
D
I wont forget it
G
I won't forget
      D
About us

(CHORUS)
F             C           G
But somewhere we went wrong
F       C       G
We were once so strong
F        C       G
Our love is like a song
          F
You can't forget it x2

D
And at last
G
All the pictures have been burned
A
And all the past
          F
Is just a lesson that we learned
D
I wont forget it
G
Please don't forget
D
Us
F               C        G
Somewhere we went wrong
F                  C
Our love is like a song
C                 G
But you wont sing along
D
You've forgotten
G
About

Us