If your Excel files are opening in Notepad on Windows PC, here's how you can reset the settings to make .xls, .xlsx, etc files open in Excel.

Once you do so, Excel files will become noticeable to the operating system again and you should make the file-to-program association once again to confirm the setting.

Launch Microsoft Office Excel 2013. You can double-click its icon on your desktop or launch it from the Start screen. Click "File," followed by "Open," "Computer" and then the "Browse" button. The ...