The melody is made of by the riff which goes something like this: 
 
E-------------------- | ---------------- 
D------------------- | ---------------- 
G-------------------- | ---------------- 
D-0-0h2p0-0---0-2-- | --0-0h2p0---0--- 
A-3-----------3------ | 3---------3---3- 
E-------------------- | ---------------- 
 
Other than that its 2 chords. 
 
 
     F5           C5         F5      C5      F5  C5  F5  C5 
They didn't have you where I come from 
      F5        C5        F5      C5      F5  C5  F5  C5  
Never knew the best was yet to come 
F5      C5          F5        C5      F5  C5  F5  C5  
Life began when I saw your face 
      F5         C5            F5   C5      F5  C5  F5  C5  
And I hear your laugh like a serenade 


F5   C5           F5          C5      F5  C5  F5  C5  
How long do you want to be loved 
      F5     C5         F5        C5     F5  C5  F5  C5  
Is forever enough, is forever enough 
F5   C5           F5          C5     F5  C5  F5  C5  
How long do you want to be loved 
      F5     C5               F5                           F5 C5 F5 C5  
Is forever enough cause I'm never, never giving you up  
 
I slip in bed when you're asleep 
To hold you close and feel your breath on me 
Tomorrow there'll be so much to do 
So tonight I'll drift in a dream with you 
 
Chorus 
 
As you wander through this troubled world 
In search of all things beautiful 
You can close your eyes when you're miles away 
And hear my voice like a serenade 
 
Chorus 
 
Chorus 
 
Cause I'm never, never giving you up