Hello Abbeysaurus,
It could be useful to check the Environment Variable first, which you can see how to do at this page:
As far as checking the registry value, you can do so by opening “Run” from your start menu and typing in “regedit” (without the quotes.) You can then navigate to the location it lists. To give an idea of what it should be set to, my current value is:
C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\