How does chess.com determine who wins a tournament if example : 3 players 1 player loses his game equally to the 2 players so tournament stats show 4loss 2win 2win and then they each lose a game to each other, who wins the tournament?

If EVERY player has exactly the same number of wins and losses, then they all tie for first. If there are just a few places that have the same number of wins, then we have a tiebreak system which is described here: http://support.chess.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=641 .

Thanks =).