It's a good practice to set up your Office apps to automatically back up your work, in case you unexpectedly lose your connection or power.
Set document recovery options
Select File > Options.
Select the Save AutoRecover information checkbox.
Set how often you'd like to backup your work.
To be safe, set a small number, so you never lose more than 5 or 10 minutes of work. Or, to make Office faster, enter a larger number, like 20.
Select the Keep the last autosaved version if I close without saving checkbox.
Change the AutoRecover file location if you like.
When you're done, select OK.
Now if something unexpected happens, the next time you open the app, you can use the Document Recovery pane to recover your Office files.
Note: Even with Document Recovery set, it's still a good practice to select Save (or press Ctrl+S) often to avoid losing work.