After the 12th Planet passes, the Earth's rotation begins again due to the factors that guide rotation of the planets in your solar system. Many humans assume rotation to be simply leftover motion resulting from some past activity such as the big bang, but rotation is guided by gravitational and electromagnetic influences on the liquid cores of planets and moons. Parts of the core move away from or toward these influences, dragging the crust with it, and as the turning motion brings those parts of the core back to where they don't want to be, motion is re-instituted and continued. For the Earth, frozen in place at the moment of passage, rotation begins again within a day after the 12th Planet moves from its influential place between the Earth and the Sun. Rotation restarts, at first slowly but then picking up speed until a day on planet Earth is much as it used to be. Just as rotation stops within a day, just so rotation returns within a day, much to the relief of the frantic survivors who fear the long day or night they have been experiencing will never end.