The physics of it say we cannot stop the Earth's rotation abbruptly, without some external forces like striking a comet... It can slowly slow down like a spinning top. It will start to wobble and the days will get longer and the weather will change dramatically as our seasons but more extreme. Over time, the earth will probably loose its water mostly due to evaporation. Life as we know it will cease to exist. The earth conditions is a delicate balance, between the sun, the he moon and the position of the Earth, any small change in any three will change the life on Earth.