if the information wasn't saved in the disk, and the computer was turned off, etc, this information is lost.
You can only "recover" information that was saved somewhere.
Excel and many other programs have (or might have) a feature called "autosave" turned on, and usually generate temporary files while you're using them. You can do some search inside your hard drive to find it (the temp files), and see if you can recover pieces of information from there.
Do you know how to use tools to recover information? Things like this product? take a look at it, do some research in the internet...
recovering information from a hard drive isn't a "just follow these steps" thing, perhaps you might want to contact someone who knows how to do it.