Hello in version 184-186 for MAC does not show me Guitar Window. On PC with windows 10 I have the latest version 2018, where everything above the same song is OK

At the same place and songs, the Big Piano window is OK

Karel

if i understand your question/problem perhaps these screen shots may help you

click on guitar in VIEWS

or use the drop down menu to load the guitar window

The problem is not that I do not know how to run the Guitar window, but the Window will not open at all

there is always something wrong but the window does not open

Maybe you have dragged the Guitar window so that it's almost off-screen. It remembers it's position between sessions. See if returning to factory settings fixes it...