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.