In your save file, bring up the Menu and note that the RETIRE option is unavailable. There are two possible reasons this might happen:
1. Earlier in the game you actually retired. That counts as a loss and so you aren't able to win the game by other means.
2. Earlier the game crashed and for some unknown reason the games now thinks that you lost. For the same reason as in #1 you now can't win the game.
The second possibility is discussed in this thread. If this is what happened, you should be able to find a record of the loss in your Hall of Fame. In either event, you won't be able to win the current game.
1. Earlier in the game you actually retired. That counts as a loss and so you aren't able to win the game by other means.
2. Earlier the game crashed and for some unknown reason the games now thinks that you lost. For the same reason as in #1 you now can't win the game.
The second possibility is discussed in this thread. If this is what happened, you should be able to find a record of the loss in your Hall of Fame. In either event, you won't be able to win the current game.