Recently, I was working on a WebAPI project and had it working in Visual Studio 2013 using IIS Express.  Then I deployed it to a standard IIS running on Windows 7 and everything failed.   Status 404 was being returned from all routes.  I tried all of the standard troubleshooting options but finally found the problem.

My Application Pool was set to .NET 2.0.  I reset it to .NET 4.0 and everything started working just fine.