Hello dolly ! : let me reply to your questions line by line :

Originally Posted by
dolly100
Is there one knows. why there is the possibility that shocks the asteroid to earth
The possibility is 100%. The only question is when. It can be tomorrow, next week, next year, or a million years from now. But it will happen again. The solar system is full of debris, and there is so much of it that some of it will hit earth for sure. Daily tons of space dust hits the earth. The bigger the pieces, the less of them exist that can hit earth.

Originally Posted by
dolly100
I know the speed of the asteroid is very high and the size is enought ,to distory the big part of eath and he heading to Earth
Fortunately most of the debris is very small (dust particles that cause shooting stars).

Originally Posted by
dolly100
But what a nothers the reasons to shocks ?
See next answer on orbit.

Originally Posted by
dolly100
Why not proceed in a stable ?
I assume you meant a stable orbit. Two reasons :
One : debris may collide somewhere in orbit and cause pieces to travel into a changed direction, possibly on a collision course with earth.
Two : the solar system travels in orbit around the galactic center. Nearby (in light years) passing-by solar systems may by their gravitational attraction change the debris course, and bring it on a collision course with earth.

Originally Posted by
dolly100
Why there is the asteroid such as this?
There are still millions of pieces of big debris floating around in the solar system.
Floating either in one orbit between Mars and Jupiter, or in another orbit far beyond Pluto.
That is all debris from the original cloud from which the entire solar system was formed.
Does that answers your questions?
:)