Hi Nicole,
We think that stars are born in huge clouds of gas and dust (see the picture below). Billions of years ago when the Sun was being born this bit of the galaxy would have had a lot of material to form stars, but now it does not.
So, it is certainly possible for a star like the sun to form somewhere else, but not in our solar system, which is where it would need to be to replace the sun. Our Sun is good for a long time to come, though - a few billion more years!
Terry
