⟩ Suppose I have lost one of the application templates in Visual Studio 2010. It’s available in the file system but not in Visual Studio… Any ideas?
Try running Devenv /setup.
Running devenv /installvstemplate might also work; but that is going to slow down overall VS performance. The /installvstemplate is a development only option that makes it easy for developer to test their templates. This shouldn’t be used on end user machines. Devenv /setup does a lot of more processing and caching to speed up VS performance.