Ruling Please . . . Is the Hand Dead?

[EasilyFound]

Two players all in. Both players misread the hands and the pot is awarded to the player with the worst hand. The player with the best hand (who called the all-in) concedes defeat, leaves the table, and gets a drink at the bar. Several minutes pass, and the player who had the best hand returns to the table, where the other player has restacked the chips for the next game (it is a heads up tourney) and the cards have not been touched and are laying face up just as they had been when the players shook hands after believing that the game was over. The player who had the best hand says he had a straight and should have won. Both players look at the hole cards and the board and agree that pot was awarded to the wrong player. The player with the best hand, who had less chips than the other guy, recalls how many chips he had left to call his opponent's all in.

How should the tourney director rule? Does the answer depend on whether the players can reconstruct the betting before the all-in?