Evolution of a star from a nebula

[Sab95]

I know that our solar system and sun evolved from a nebula of a giant star.. but what happened to the remaining of the star.. entire star cannot go boom.! at least some remaining portion of the primordial star should have existed in the form of a neutron star or a white dwarf. If it existed what happened to it..

 

[Bandersnatch]

The question is not clear to me, so allow me to paraphrase to what I think you're asking. Correct me if that's not what you meant:

"Since the Sun and other stars are thought to have formed from gas containing heavy elements produced in the cores of earlier generations of stars, where is the remnant of the star that was our solar system's parent?"

This question is taking a very naive view that all the gas that ended up in the solar system came from one dying star's ejecta.
This is hardly the case.
Recent stars(aka population I stars, which includes the Sun) are thought to have formed from the clouds of primordial hydrogen-helium gas that over the age of the universe have been contaminated by heavier elements from older stars.
While the actual cloud collapse to form the protoplanetary disc can be triggered by one or many supernovae exploding in the neighbourhood and producing pressure waves that compress the gas(and supplying short half-life elements), these are not to be thought as exclusive progenitors of our solar system. They're just a part of a larger process involving many now-dead stars and lots of material that has been around since the beginning of the universe.

Still, you might ask "where are the remnants of these most recent stars that had triggered the formation of the solar system?", which is a question that might never be answered.

You see, there are two factors making the detection of such stars difficult.
First of all, over the five billion years of our solar system's age, we must have traveled quite a bit of a distance from the stellar cluster that was our cradle. Which part of the sky should we look at to find the husks of these old stars? How could we even say if this was indeed one of the stars we're looking for?
And second of all, white dwarfs(and neutron stars too, unless they're pulsars) are very dim objects, getting only dimmer as they cool down over time. It's relatively easy to detect them when they're orbiting another star, or there's a planetary nebula with one at its centre(i.e.the death of the star must've been recent).
But after five billion years your guess is as good as mine.


As a final correction to what you said, supernova explosion can indeed destroy a star. Look up "type Ia supernovae".