what is NOTHING , before the big bang and after the big crunch?

The standard model of physics as it exists today is amazingly strong. It can accurately predict phenomena from the scale of star and galactic interactions to that of subatomic scale. However, it is a model of our universe and as such has no bearing on that which is "outside" of our universe. The laws we have constructed only hold water AFTER the big bang. When the universe was approximately a singularity the rules that dictated the universe were very different than what we see today. The same applies to black holes. We simply don't understand how things work around a singularity. Time, being a part of our physical model, similarly breaks down in these instances; thus there is no meaning to the word "before" when it comes to the big bang. We have no conception of time beyond a certain point.

One thing you can be sure of though is that it isn't a good idea to picture an outside to the universe, neither spatially nor temporally. There is no "edge" to the universe thus there is no space beyond it. Time breaks down when the universe approaches the infinite density so there is no before or after.

Also, the idea of there being a Big Crunch has been all but thrown out. The evidence doesn't suggest the universe is falling back in on itself nor even slowing down. The rate of expansion is INCREASING. The "end" of the universe will be due to heat death. That is to say the universe will expand forever until one day all the stars die out, all the white dwarfs become black from the cold, and block holes fizzle away due to Hawking radiation until there is nothing to constitute this universe save errant particles that are so far apart that they never meet.

You're trying to picture it which is the problem. They say that there was just nothing, including spacetime so there could be no expanses of darkness as that requires space. But the Big Bang is still just a theory, so who knows?

To be as undemanding as i can, this question can not be replied using the understanding that people presently very own. we can all take a seat here and speculate on huge Bang Theories, Creators, Divine Forces, and Cosmic Forces all day and night... regrettably, we will not provide an answer. regardless of the undeniable fact that it truly is a exciting debate even nevertheless!

There is only one *correct* answer to your questions --- science does not know. There are several concepts about pre-Big Bang, but there is not one bit of evidence to support any of them.

The so-called "Big Crunch" theory has been pretty much been killed.

nothing means no matter, no energy, no space, no time.