A customer ran into an issue with excel it was 'The file does not have a program associated with it for performing this action. Please install a program or, if one is already installed, create and association in the Default Programs control panel'
Here are a few articles I sent over for them to fix the issue as well as a YouTube visual.
Windows 7 or 8 specific: http://www.winhelponline.com/blog/fix-file-association-error-explorer-in-windows-7-8/
YouTube How To : https://www.youtube.com/watch?v=61C_J89pzpQ