It is not medically possible unless the person is clinically dead. However, a person can go into a coma for this time and wake up from it. It is also possible during surgical heart operations where the heart is stopped for a few hours and then restarted, during this time, the person is considered to be clinically dead.
There was a great Magician(Russian) back in 1940's who can stop his breathing(die) for an hour...he tried to return 2 life after a couple of hour but eventually he died and dint return bck !!! its impossible
There are cases in which people had been considered dead and had been buried rather alive! (Quite a long time ago, mind you.) However, that's because they lacked the technology and knowledge that humans have now! So, naturally, it depends on your view of the question. People can seem dead, but are they really? Even being announced clinically dead can sometimes be a mistake. Often times, people have the appearance of death... but they're still very alive. Ever read Romeo and Juliet? In Romeo and Juliet, Juliet is given an elixir that gives her the appearance of death... but it wears off in a series of hours. Voila.