Which year will the earth be destroyed?

As a planet, billions and billions. The Sun will run out of hydrogen in about 4.5 billion years, and turn into a red giant, the outer edge probably touching the surface of Earth, melting the surface but the planet will still exist.

As a repository for life, a lot less than you think. Current estimates place that life on Earth will slowly disappear in about a billion years time as the Sun get hotter. Water will evaporate into space and all life will die.

That's an astronomical perspective, human nature may make it a lot shorter than that.