Intro/Outro/Verse: F#5  F#5  D5  C#5 . I couldn't tab the exact base line, but I 
tried to make similar one, here it is:

E | 2-2-------------------- | 2-2---------------5-7- | 
A | -----4---4-5-5--5-4-4-- | -----4---4-5-7-5-4---- | 
D | ------4---------------- | ------4--------------- | 
B | ----------------------- | ---------------------- | 
G | ----------------------- | ---------------------- | 
e | ----------------------- | ---------------------- | 

   Verse:

   F#5   F#5    D5    C#5
Summer came to an end,
   F#5   F#5    D5    C#5
We're saying good bye to friends,
   F#5   F#5    D5    C#5
We met this month,
We'll keep in touch,
   F#5   F#5    D5    C#5
I wish time would stop instead.

   F#5   F#5    D5    C#5
'Cause I don't wanna say good bye,
   F#5   F#5    D5    C#5
When I'm caught up in your eyes.
   F#5   F#5    D5    C#5
I wanna stay like this,
Like our first kiss,
   F#5   F#5    D5    C#5           
That brought my heart to life.
   
   F#m E before the chorus

 Chorus:
 A5     D5   A5
Don't let go,
 E5               A5     D5   A5
Tell her so she won't let go.
 E5
She may never know.
 A5
So tell her,
 D5
I should tell her,
 A5                 E5
Before my heart explodes.
 A5     D5   A5
Don't let go,
 E5                 
I won't let you go. 

 F#5  F#5  D5  C#5 x2

 F#5  F#5    D5    C#5
The nights are getting cold,
 F#5  F#5    D5    C#5
And the days are hard to hold.
 F#5  F#5    D5    C#5
You're months away and miles from me,
 F#5  F#5    D5    C#5
But the memory's still gold.
 F#5  F#5    D5    C#5
I think about them all the time,
 F#5  F#5    D5    C#5
That summer when you were mine.
 F#5  F#5    D5    C#5
Before I caved in, my words felt thin,
 F#5  F#5    D5    C#5     F#5   E5   
Don't wanna say good bye, goodbye.

 A5     D5   A5
Don't let go,
 E5               A5     D5   A5
Tell her so she won't let go.
 E5
She may never know.
 A5
So tell her,
 D5
I should tell her,
 A5                 E5
Before my heart explodes.
 A5     D5   A5
Don't let go,
 E5                 
I won't let you go. 

 Bridge:

D5      A5               E5
Please take me back to summer,
   F#5   E5        D5
So I can let you know,
D5    A5                  E5
This year's been such a bummer,
   F#5   E5        D5
Because I let you go.
D5      A5               E5
Please take me back to summer,
   F#5   E5        D5
So I can let you know,
D5    A5                  E5
This year's been such a bummer,
   F#5   E5          A5   D5   A5   E5  x2
Because I let you go.

  Chorus x2

  Intro/Outro: F#5  F#5   D5   C#5  x4