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.

Click "Microsoft Excel" from the Recommended Programs section and click "OK" to reset the registered default program to Excel for that file type. Repeat for each file type you wish to reset.

If you cannot open an Excel file and see Excel cannot open the file because the file format or extension is not valid error, see this post.

Pro Microsoft Excel is making a major change around blocked file types - here's what we know News By Craig Hale published August 1, 2025 ...