Only from a backup copy you previously saved.
That is not correct. If you're on Windows and have system restore turned on for the drive the file is on, you may be able to get a previous version back.
Find the current version of your file in Windows Explorer, right click on it, choose properties, then at the top, select the tab "previous versions". If you've had restore points (usually you do) there should be one ore more old versions that you can choose to restore. I stumbled across this by accident and it has saved me numerous times.