This is the song from the Hindi movie 'Rock On!' the music has been composed by the trio
Shankar Mahadevan, Ehsaan Noorani and Loy Mendosa (Official Website -
The Singer is also the same person who acted as the lead vocalist of the band called 
featured in the movie, Farhan Akhtar

[These chords were written by me for a friend who wanted to play this for a fest, and
he was a real greenhorn I wrote the Chords EXACTLY under the parts of the words to get him
change chords in time]

The song is in C major... with occasional changes :) i'm pretty sure it's 100% correct

Notes:

Hold the Open Chord shapes for the following:
Em C Dm

Hold Barre chords for the following:
F G Bb Bm

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Tum ho to gata hai dil
       CTum (x32010@1)nahi to geet kahaan
      Dm (xx0231@1)         GTum (320003@1)ho to hai sab hasil
       CTum (x32010@1)nahi to kya hai yahan
      Dm (xx0231@1)            GTum (320003@1)ho to hai sapno ke jaisa hasin Ek sama
F (133211@1)              Bm (x24432@1)          Em (022000@1)F (133211@1)C (x32010@1)Jo tum ho to
   GYeh (320003@1)lagta hai
    EmKe (022000@1)mil gayi har khushi
   Dm (xx0231@1)     F (133211@1)Jo tum na ho
   GYeh (320003@1)lagta hai
    EmKi (022000@1)har khushi main hai kami
   Dm (xx0231@1)            FTum (133211@1)ko hai mangti
G (320003@1)Yeh zindagiiii....iiiii.....OOOO...oooo..
         C (x32010@1)      Em (022000@1)      F (133211@1)    C (x32010@1)O  ho  o  ho
Dm (xx0231@1)   BbOo (x1333x@1) O  o  ho
CWoh (x32010@1)o  ooo  o
Dm (xx0231@1)   BbOo (x1333x@1) O  o  ho
C (x32010@1)Tum ho to Rahein bhi hai
       CTum (x32010@1)nahi to raste kahaan
      Dm (xx0231@1)          GTum (320003@1)ho to yahan sabhi hai
       CTum (x32010@1)nahi to kaun yahan
      Dm (xx0231@1)         G (320003@1)Tum ho to hai har ek pal meherbaan Yeh jahaan
F (133211@1)               Bm (x24432@1)        Em (022000@1) F (133211@1) C (x32010@1)Jo tum ho to
   Ghawa (320003@1)main bhi
  EmMohabbaton (022000@1)main rang hai
  Dm (xx0231@1)          F (133211@1)Jo tum na ho
   GTo (320003@1)phir koi
   Emna (022000@1)josh na umang hai
   Dm (xx0231@1)     FTum (133211@1)mile to mili
G (320003@1)Yeh zindagiiii....iiiii.....iiii...iiii..
         C (x32010@1)      Em (022000@1)      F (133211@1)    C (x32010@1)O  ho  o  ho
Dm (xx0231@1)   BbOo (x1333x@1) O  o  ho
CWoh (x32010@1)o  ooo  o
Dm (xx0231@1)   BbOo (x1333x@1) O  o  ho
C