I currently upgraded to CC and now all of my CS5 InDesign files are listed as exec files. I tried changing the extension to .idml and .indd but I then get an error message that says" A ID may not support the file format, a plug-in that supports the file format may be missing, or the file ay be open in another application.
How do I open my CS5 InDesign files in CC? :O
Did you uninstall CS5 after installing CC? It sounds like the icon handler, and maybe some other stuff, has been damaged.
If the file extension was .indd, it should remain as .indd -- changing a correct extension can never help. Do they open if you name them properly and use File > Open...?