What is behind Comet ISON?

[guohua]

So where did this comet go? Back to the oort cloud or is it due back anytime soon?

You want NASA's official story?

The much-anticipated flyby of the sun by Comet ISON on Thanksgiving Day 2013 is over, and instead of becoming a Great Comet….
"Comet ISON fell apart," reports Karl Battams of NASA's Comet ISON Observing Campaign. “The fading remains are now invisible to the human eye.”

They say it fell apart.
But the question is why didn't they show the Comet on the Live Feed?

On the morning of Nov. 28th, expectations were high as ISON neared perihelion, or closest approach to the sun. The icy comet already had a riotous tail 20 times wider than the full Moon and a head bright enough to see in the pre-dawn eye with the unaided eye. A dose of solar heat could transform this good comet into a great one.

If the Comet had a Tail 20 time larger than the Full Moon, why didn't everyone see it?

Cameras onboard the Solar Dynamics Observatory followed the comet all the way down to perihelion and saw … nothing. 
“We weren’t sure what was happening,” recalls Knight.  “It was such a roller coaster of emotions.”

The researchers were surprised again when a fan-shaped cloud emerged from the sun’s atmosphere. No one knows for sure what was inside. Possibilities include a remnant nucleus, too small for SDO to detect, or a "rubble pile" of furiously vaporizing fragments. By the end of the day, Comet ISON was nothing but a cloud of dust.
Source

I still do not believe it was an actual Comet. But that is JMHO