Will the stars and sun stop shining one day? The answer is yes; but not for many thousands of millions of years yet. Our sun will probably stay at its present size for another 5000 million years before it begins to change.
First the centre of the sun will get smaller and hotter. The outer layers will be pushed out further by this increased heat, so the sun will grow in size. It will become a red giant star, so it will grow to about a hundred times its present size. As it does so it will probably swallow up the planet Mercury.
After about another 1000 million years , the sun will begin to shrink. It will become no bigger than our earth, and it will change its colour from red to white and become a white dwarf. After thousands of millions as a white dwarf , the sun will have used up all its energy and lost all its heat. In the end, it will become a cold dark body, called a black dwarf, giving off no light or heat.