What are the actual reasons of jetlag? having read about reasons like,
Time Zone difference, Cabin Pressure, Dehydration, stress, sleep and
rest etc.
which affects the most?

does listening to Schumann resonance frequency of 7.83 Hz really reduce jetlag?
( i used it using binaural beats ) and felt better after that.

would like to know if Sound therapy can really be the solution for Jetlag,
instead of advertised medical pills of melatonin or Accupuncture
methods which are difficult to follow every 2 hours.

any significant scientific research data, facts sheet with support will help.

Interesting question.

It is said that jet lag hurts more when you lose time (i.e. by
travelling West to East) than when you gain time and that is certainly
my experience.

If it works, use it.  My experience is the reverse of Probono's, well,
concerning flights from Europe to USA.  Actually I find that jetlag is
overcome by adrenalin on flights from home in either direction:  the
adventure, anticipation, whatever the reason for the trip.  Coming
back home is a letdown, nothing to keep me from feeling disengaged and
sleepy in the middle of the day.

Light therapy is said to be good, and agrees with my experience.  Try
to arrive with a good portion of the day still ahead of you and get
out in the daylight, forget that it is 2 am back home, and keep busy. 
By evening, you will be tired enough to sleep and start the new day
refreshed.

Of course, during the flight one shouldn't imbibe too much, and do all
the things suggested for surviving long flights.

If you travell by a propeller driven aeroplane then  obviosely jet lag
will not occour
Stands to reason dont it?