holing a ard by accident

ok so four players first player plays a 2 second plays a queen third lays a six fourth lays a six then for goes so player four moves one for a go player one plays and so on player four at the end of the game throws a six notice that she could have played it the hand before giving her point but missed that chance but the question would be what should happen to that six does it stay in play or dos it become a dead card.

Renigging

I believe your question relates to what is called renegging or renege. A renege is a failure to play a card that could have been played. A player may correct a "go" call before either player pegs a point or before the opponent plays a card. Thereafter, when a renege card is played, the opponent may claim a renege up to the time he or she plays the next card or announces the count of his or her hand. Judges shall be summoned. Any cards played after the renege occurs or the pegging of a "go" shall be retrieved by both players, and any points pegged (or scored) are retracted. The non-offending player receives two points for each card that singly could have been played (judges confirm number of cards). The nonoffending player decides if the reneged card(s) will be dead or played. Play continues, and all cards in both hands and crib are counted. For example, if the count is 25 and a player whose turn it is holds A, 5, and 6 and does not play any of the three cards and says "go," that is a "triple regnege," and the opponent gets six points (two for each card). Hope that helps!