问题
I'm new to C# Programming, and instead of just letting me run the code by pressing F5, "Attach..." appears where the Run button should be and it won't let me run the code. This has happened me twice by now and I don't know how to make the "Run" button appear again, because I can't test any program I write.
回答1:
Make sure you have your solution opened, then right click on your project > Set as Start Up Project
回答2:
You probably used option recent files which is next to recent projects and solutions option. You still can use recent projects and solutions menu item. There is no bug here.
回答3:
Go to %appdata% and delete the Visual Studio folder, this will reset Visual Studio and fix this error.
来源：https://stackoverflow.com/questions/30443640/cant-run-program-because-it-asks-me-to-attach-on-process