1. without the sun, the planets (including earth) would have nothing to orbit. we would then fly off into the coldest part of space--temperatures would be so low that nothing would be able to live on earth (more on like in a second). and earth would be so cold.
2. if there was no sun, Photosynthesis could not happen. without photosynthesis, plant would die. plant make oxygen (through Photosynthesis). so without plant, there would be no food, oxygen and of course, life for people.
3. You will not able to see the beauty of surroundings that GOD had made.
4. sun can kill microbes. that is why it is important to put out in the sun the carpets, blankets and eiderdowns that cannot be washed regularly. expose to the sun confess the skin a bright, healthy look and increased elasticity.
5. the sun also plays a role of a big anchor, which creates gravity that keeps our planet and the other planets of the solar system in a small space. if it weren't sun, our planet would simply fly off loose into the universe.