The windows.old directory wouldn't contain any personal data only system files. If you waited 30 days or more then that directory would have been removed. If it's been a lot longer than 30 days then the space where those files resided would most likely of been overridden with new data. If it was recently deleted you may be able to recover them with a tool such as GetDataBack, Recurva, or testdisk. Recovered data should be written to a different disk than the one being recovered from.