With the advent of November and NaNoWriMo, naming files and version control becomes an issue, especially for new and beginning writers.
For every new document you create, I recommend that BEFORE you do any work whatsoever, you give the file a working name and save it to whatever folder you normally work out of.
Do that immediately.
Do it while the page or spreadsheet is still blank, before you write the first line.
Most people never had more than a few personal files to manage. For this reason, they have no concept of how easily something that should have been simple can veer out of control.
This is where a good system of version control comes in handy. The worst thing that can happen is when you accidentally save an old file over the top of your new file or delete the file entirely.