what if the earth stopped spinning?

Immediate effects? We would all go flying about 800mph-1000mph due east.

Earth is rotating at a speed of about 1100 miles per hour. If our planet suddenly stopped rotating, the atmosphere would still be in motion at that speed. The atmosphere would be moving so fast it would literally sweep the land masses clear of anything not anchored to bedrock, this would mean rocks, soil, trees, buildings, people and animals. All would be swept up into the atmosphere.

If the Earth's rotation slowed down gradually over millions of years, and this is the most likely scenario, it would be a very different story. If the Earth slowed down to one rotation every year, called synchronous rotation, every area on Earth would be in either sunlight or darkness for one year. This would be similar to what the Moon goes through where for two weeks the front side of the Moon is illuminated by the Sun followed by the front side being in darkness for two weeks

If it suddenly slammed on the brakes then everything would be so destroyed, it's doubtful that anything remaining would be bigger than a grain of sand. If you've seen tornado damage from an f5 (avg. wind speed about 350mph), imagine that tripled.

Gradual slowdown would still be bad news in the long run. World ending climate change, increase of earthquakes, etc. But still, better than the first scenario.