Kya Hua Tujhe Bechain Dil Ho Raha is a beautiful hindi song from 2002 bollywood film Tumko Na Bhool Payenge. This song is composed by Dabbu Malik. Alka Yagnik and Sonu Nigam has sung this song. And of course lyrics for which you are looking is written by Salim Bijanauri.
Lyrics : Salim Bijanauri
Music : Dabbu Malik
Singer : Alka Yagnik, Sonu Nigam