Somehow part of my syntax highlighting for C# code has disappeared in the VS 2012 IDE. Uninstalling, rebooting, and reinstalling does nothing, nor does resetting the colors
It work for download this "Productivity Power Tools 2012" and install, after install this tool get this steps go to Tools -> Options -> Productivity Power Tools and turn off the "Colorized Parameter Help" option.
This fixed the keyword as syntax ActionResult is not set for default black color and highlight problem resolved.