Despite being a britany song this really does sound good on the acoustic
check out matt cardle doing it live....http://www.youtube.com/watch?v=K4mfUyjfuA0

Tuning: standard
Chords:

  Bm        Bm/A#     E7sus4/A      E        F#
e|-2----------X----------5----------0--------2-|
B|-3----------3----------5----------0--------2-|
G|-4----------4----------7----------1--------3-|
D|-4----------4----------7----------2--------4-|
A|-2----------1----------5----------2--------4-|
E|-X----------X----------5----------0--------2-|

best using all down strokes

Bm
Oh baby, baby
    Bm/A#             E7sus4/A
How was I supposed to know
     E                F#    
That something wasn't right here
Bm
Oh baby baby
  Bm/A#                  E7su4/A
I shouldn't have let you go
    E                 F#
And now you're out of sight, yeah
Bm                       Bm/A#
Show me, how you want it to be
        E7sus4/A
Tell me baby
                 E        F#
'Cause I need to know now what we've got


Chorus:
Bm               Bm/A#
My loneliness is killing me (and I)
E7sus4/A          E              F#
I must confess, I still believe (still believe)
Bm                      Bm/A#
When I'm not with you I lose my mind
E7sus4/A
Give me a sign
E           F#
Hit me baby one more time

exact same pattern throughout the rest of the song

来源：www.ultimate-guitar.com