I am using Visual Studio 2013.
For some reason, the Start Debugging button is missing on my toolbar. Also, when I am debugging, the Stop debugging/Pause buttons are
If you have multiple projects you may want to make sure that the project you want to debug is set as "Startup".
You can right-click the project and click "Set as StartUp Project".
This was the solution for me because it did not correctly load my MVC project; defaulting it to another project for startup.