Find a copy of the document
There might be an older copy of your file, which might save you some work as you’ll only have to update it if any changes were made between the copy and the version that’s lost.
But unless you (or someone) ticked the option, Office doesn’t automatically create copies of your documents. But if enabled, there should be a second version of your file called ‘Backup of xxxx’ where xxxx is the original filename.
For future reference, and not that you really want to hear it now, but to force Office to make copies you need to go into the options, find the Save section and look for an ‘Always create a backup copy’ setting. Not all versions of Office have this, but you will find options there to save AutoRecover data – set the time between auto-saves to a few minutes, and that way you’ll only ever lose a small amount of work.
Some cloud storage services, including Dropbox, automatically create copies (versions) of your files each time you edit them, so it’s well worth checking for this if your file was ever saved to the cloud.
Another glimmer of hope of finding your file comes in the form of Windows Shadow Copy. This isn’t available in all editions of Windows, but you can check if yours has it and whether or not it’s enabled. To see if there’s an older version of your file, launch Windows Explorer and right-click on the file that contained your document. Click Properties and then look for a Previous Versions tab. If there is one, click on it and you should see a list of dates. Double-click on a date you think the file should have existed and look for the file.