Answer by Kip for Double Clicking an Excel File Will Open Excel but not the Spreadsheet itself

I had this problem after installing Office 2016 (Office 365). I kept finding the instruction about the DDE option, which did not work for me. The following solved it for me:

1. Open Control Panel
2. Open Programs and Features
3. Select Microsoft Office
4. Click Change button at the top
5. Select Quick Repair.

This took me something like 3-4 minutes. This solved it for me.