There is no mystery really it just happens to be the latest date from the Doom Sayers for the World to End.
I suppose if they keep saying it for long enough one day they will be right.
The year will only be 2012 if you are a Christian because they have tried ( a few times) to back calculate as to when Jesus was born.
I think the latest guess is 6 BC which makes this year 2017 not 2011 so if the world ended in 2012.... We missed It.
As for the tosh about the Mayan Calendar ending in 2012 the Mayan's and the Christian's never met so the chances of it being the same year as next year are Zero...
So I would'n worry about it and just get on with life and enjoy it.
PS Just in case you don't believe me I don't advise running up a huge Credit Card bill with the expectancy you won't have to pay it in 2013....