sounds like its corrupted. Have you turned your PC off without exiting game?? Unfortuantly there aint much you can do. Either go on the SI website and they maybe able to fix it or if you have a rolling file save then load that one up. This is another file which will take you back to when your original save was last saved. The more rolling file saves you have the more they will be updated so you don't have to replay months of the game. Good luck, hope this helped! :)