I would like to know the views that the historians of this age give about the destruction of the Indus Civilisation. Some views were like foreign invasions, natural disasters and epidemics. But I would like to know the latest views.
We don't really know.
For comparison, note that historians are still arguing over what exactly caused the fall of the (western) Roman Empire, which at the time was the most literate Civilization on earth. If they can't agree on that, it is probably not reasonable to expect certain knowledge about the exact cause for the decline of a bronze-age civilization that was barely literate (and what little we have undeciphered), and had no literate neighbors.
All we can really know is what archeology can tell us. It does appear that it declined and eventually faded away over a long period of time, rather than just mysteriously disappearing one day. That makes disaster theories like destruction at the hand of an Ayrian Invasion much less attractive than they used to be.
The current darling appears to be Climate change (drought). However I should warn you that Climate change appears to be the go-to explanation these days for the decline of any culture we don't have good records for (and some we do). This may be due to the fact that it really has been the major stressing factor for cultures in human history, but the cynic in me has to wonder if its just a scholatic fad.
+1 for citing climate change. Is it not an assumption to say that they were barely literate? Rivers from the Himalayas change their course quite often and it is still a problem in the indian subcontinent. The extinction/change of course of the ancient river saraswati could be a reason too. http://www.stephen-knapp.com/recent_research_on_the_sarasvati_river.htm