XPS 13: Keyboard Button sudden not working

Hi, i own a Dell XPS 13 (2012 model)

Today when i was trying to use my XPS 13, the "Tab" "Caps Lock" and "Shift" button does not work anymore.

I have read other questions post in here and i tried to boot up to the bios and Load default setting and it couldn't work 

What could possibly happen? Please help. I need this laptop for my studies purpose and this would affect my productivity :(