"Demonetization exercise was a total and epic disaster and it shocked the economy without fulfilling it's motive of "war on black money" as 99% of the invalid notes were returned to the RBI."
That was exactly the point. The fact that 99% of notes were returned indicates that demonetization was a success.
The whole idea was to stop large cash transactions from occurring in secrecy where they cannot be taxed.
Any economic problems resulting from demonetization are short-term. In the long run, moving to electronic transactions will be of great benefit to India.