Have any frozen humans ever been brought back?

Not yet, but I hope so. I'd love to be around when that day came. Imagine what they might be able to tell us about our own fate, the knowledge possessed by no person living today or having ever lived since humans came to exist. I think it would cause more harm than good though and eventually it would result in extinction of the human race and probably obliteration of nature itself as we know it. Think about it, if cryonics proves to be fact then it's not difficult to assume what will happen. It would become the biggest money market the world has ever seen, bigger than porn even, bigger than all of the sex industry, drug industry, music industry, movie industry, sports industry, etc. etc. all combined and it would happen overnight, whereas these other empires were built over a long period of time, the industry of immortality would appeal massively and instantaneously to almost every living human on the planet. Obviously that would mean eventual overpopulation on the most extreme level. Overpopulation is a serious concern right now without even dealing with the notion of nobody staying dead anymore. Roughly 6 billion living humans inahabit the planet. That would double within decades, continue doubling faster and faster and at some point there would be total chaos and we'd destroy ourselves or be destroyed by some other means. It's the only logical conclusion. It would be the ultimate irony....the cure for death becomes the cause for extinction. Nature took an enormous risk giving rise to human intelligence. Never before has nature given birth to a species who not only threaten to willingly destroy themselves, but destroying nature itself as we know it. It's quite profound to think about. We all know how powerful nature is, it can wipe out any one of us or every one of us at any given moment and we'd be powerless to stop it at this point. But if nature allows us, and we allow us to continue progressing as a species eventually we will be more powerful than nature itself could imagine. Nature has always been the one in charge, it has always been the one to decide the fate of all life on the planet, nature selected dinosaurs for extinction, the most physically enormous and powerful living things ever to walk the earth, yet they were powerless against their own demise. Nature has always before enjoyed complete power and control, it still does, but if we continue as a species, then those days are numbered, humans will become more powerful than nature itself could imagine.

The method you speak of is Cryonics, often mistakenly called cryogenics. No human has ever been revived as of today, but the medical community is optimitic about the future and what our technology will become capable of.

Wikipedia has a full description and links to Cryonic research.