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.

If Excel is not opening on double-click or not responding on your Windows 11/10 PC, take a look at the addons first, or else follow these suggestions to resolve the issue.

How to Open Excel 2007 Files As Separate Windows. If you work with multiple Excel files over the course of a workday, and especially if you use a dual-monitor setup, you might wonder how you can ...