Can plasma turn back into gas, solid, or liquid? I wanted to know if, since basic chemistry teaches you that states of matter can be changed, I was wondering particularly about plasma.
I know that virtually all of the Sun is plasma, so I was wondering if it's possible to de-ionize the sun, and convert it into a liquid and melt it?
I realize this question is laughable, but if the Sun is made out of plasma, and it is converted into a liquid, would there be any immediate benefit in drinking it?
Like, what nutritional value would there be in drinking the Sun? I realize this is going off topic to dietary/nutritional concerns, but as physicists can't we all take a step down?
Now, I hope you are all aware that this question is meant to be both enjoyable and scientifically credible, so please don't jump the gun and attempt to ionize my question.
 A: Sometime a plasma is called the fourth state of matter, in the sense that to go from the gaseous phase to the plasma phase you have to provide enough energy to ionize the atoms/molecules of the gas; this energy can be seen as the "Latent Heat" you need for the phase transition.
However, this is not a satisfactory way of thinking of a plasma. For instance, the plasmas created in high power laser-matter interaction (as a reference, this is a very good book by P. Gibbon), have number densities of the order of $10^{23} cm^{-3}$, so well in the solid state density regime. Anyway, at even higher densities (and very high temperature) a plasma (the solar plasma, for instance) can have dynamical properties which resembles very much those of a liquid, in the sense that a fluid mechanical description (or MHD, if the plasma is magnetized) captures its dynamics.
For the sake of curiosity, there are even studies on "ultracold plasmas", which have very remarkable properties like the fact that if they are let expand while cooling, they can crystallize and form ordered structures called Coulomb crystals (you can look here if you're curious). A phase transition like that, from plasma to solid, is an even higher step than sublimation!
From the nutritional point of view, if you consider that a spoonful of a neutron star nucleus is more massive than the entire Earth, I think you'll need some billion of years of gym to get your silhouette back again!
A: If we assume an ideal gas, $PV=nRT$, then if we manage to keep the sun at a constant pressure and somehow decrease its volume, its temperature necessarily decreases as well. Thus, it would be physically possible to decrease the temperature enough that it re-ionizes to form a gas.
However, doing so would certainly kill us all, since there'd be no heat for our tiny planet.
Last year, a British girl nearly died after drinking liquid nitrogen (liquid at 77 K) due to a perforated stomach. Drinking liquid hydrogen (liquid at about 20 K) would be worse, likely leading to your death.
A: In a plasma it is hard to specify the state as solid, liquid, or gas but a good way to think about it is to ask what is driving the interactions in the plasma. Literature often cites the plasma coupling parameter $\Gamma=Z^2 e^2/(k_b T a)$ where a is proportional to $(number \  density)^{-1/3}$, T is the temperature, and Z is the charge number. This can roughly be though of as the ratio of kinetic to potential energy of the particles in the plasma. $\Gamma$ < 1 is generally thought of as a "classical plasma", but for $\Gamma$ > 1 you begin to see some "fluid like" behavior ( meaning correlations ), and for very large coupling parameters $\gamma >$~$ 175$ the ions form the coulomb crystals mentioned above, while the electrons behave classically. The thing to take away is that the strength of particle interaction determines the whether or not the behavior of a plasma may have similarities to solids or liquids. 
A: If we de ionise sun it would re ionise itself into older star due to huge gravity due to mass.
we can only stop its fusion in its some parts and remove them which would give us gaseous hydrogen which we have to liquefy in low pressure and temperature
A: I'd like to suggest you to check the definition of plasma. Actually, there's no clear demarcation between plasma and general material. If the ionisation parameter like Debye length is not notable, or the typical frequency is negligible in your case, the plasma is no plasma any more. While in the sun, of course it's possible to de-ionize it and it will decay time by time and finally meet its end when the radiation pressure is no longer able to balance the gravity. Noting that the difference between solid and liquid is the structure of molecule or crystal, at that certain time, the sun will become a "solid ball" while of course with a remarkable density.  
A: Though I'm not a physicist, it is my understanding that plasma can turn into gas (recombination) and gas can turn into plasma (ionization) but that no other physical phase changes can occur.  
A: You would immediately die. The temperature of liquid helium and liquid hydrogen would freeze your mouth, neck, digesting system and organs had contact with. By the way, you will explode after drinking Sun's gas.
A: Plasma can be changed to gas because when a star dies it blows up usually and then it changes to gas. So basically plasma can be changed to gas only if it's super heated or gets super cold
A: I asked a similar question. honeste_vivere's answer was partial, but here goes the meat and potatoes: ..."the term for going directly from solid to a plasma is ablation and/or spallation with ionization"...
