After masturbating I washed it with water but not properly used a towel to wipe my part.then washed my hands and again used the same towel.then wore my underwear.I used my fingers to masturbate a girl.can there be chances that my fingers would have sperms and that can make her pregnant?? Do sperms die with water? Can they be passed on to hands from towel?

No way... but keep away from girls until you are older and receive sex education.