Recover a file if you close without saving
Files are automatically saved every 10 minutes, after this time you can recover them.
Applies to: Word, Excel, and PowerPoint. Example used: Word
When you close a file that you’ve made changes to, you’ll be prompted to save the changes.
If you press Don’t Save by mistake after it’s been AutoSaved you can recover the document whilst you are logged on, even if it’s a new one that you haven’t saved before.

You can also recover files using the facility on Windows 7