Wouldn't that be terrible! Many things could happen, all of which are catastrophic to human life. If the Earth lost its' orbital momentum, then it would fall into the sun and be vaporized. If it accelerated out of its' orbit, we would all freeze to death. If our orbit was altered it is possible we could even collide with another planet or asteroid belt, and be pummeled into oblivion. Better hope we stay in orbit :)
