theory of the world suddenly stopping...?

We would all be crushed, an example would be; if you have ever played on the spinning wheel on a playground, where you try to hold on when its spinning, you experience weightlessness as you are pushed away from the heavy center of gravity in the middle. The opposite would remain true, since we are used to spinning at the high speed experiencing slight "weightlessness" we would be returned to a normal gravitational state if we were to stop spinning, crushing us all.

No, its not possible by any reasonable means. You'd essentially have to either a) build a world sized clamp that somehow anchors itself in space, or b) introduce a gravitational body of such intensity that it gravitationally locks the earth in a very short period (destroying it in the process, of course). Neither scenario is particularly likely. :)

and ps. to The Voice....you need to go and look up gravity, seems you may have a few misconceptions.

Stop? What do you mean stop? The world is spinning on its own axis, and orbiting the sun. The solar system is rotating around the center of the galaxy and the galaxy is moving relative to other galaxies. Cease to exist, yeah, eventually, but stop? Impossible.

I assume you mean stop rotating about its axis. The earth seems pretty solid when we walk around on it, but beneath its thin rocky crust we float on liquid magma. So because our earth is a rather squishy semi-fluid, it would be very difficult to grab it to produce the tremendous torque it would require to decelerate and halt its rotational motion.

I cant think of any realistic scenario that would halt the earth from rotating.