The pole shifting is a phenomenon when the earth switches it's poles, So North pole becomes South and South pole becomes North(Well it's much complicated than that actually).
But as like everyone is saying this pole shift will not occur overnight or in matter of days or months.. It will take a Freaking 1 million years for a pole shift to start and complete.
So, there is no need to worry about the end of world so soon with a Pole Shift.
Planet X or Nibiru
According to Somalians there exists a planet Niribu which circles the sun every 3600 years and when it comes there come the tough times on earth.
This is not happening because, If that Planet X is coming towards Sun/Earth, then it should be visible by now. And for people who say the planet Hides behind the Sun, Get out of childish theories.
But there is One event which can actually make the world to come to a stand still, and they are called Super Volcanoes
There are a few Super Volcanoes which are sleeping quietly from thousands of years. If one of them wakes up some day then it is the actual Dooms Day. The entire earth will go dark completely covered in dust clouds on their eruption.
But there is no proof available that they will go off on this date. So they can go off any time. So no need to worry until they go off.
With Many more theories for dooms day floating around, I feel the world is not going to end with some astronomical event or some blast it will come to a standstill due to fear.
Stop Worrying... Live your Life normally... Have a Beer... Cheers... :)