what is the code to launch a file?

[dilettante]

There really hasn't been a need to resort to an API Declare for some time:

    'Reference to Microsoft Shell Controls and Automation,
    'Shell version 5.0 or later (WinMe, Win2K, or later):
    With New Shell32.Shell
        .ShellExecute "C:\test.pdf" 'Additional optional arguments can be supplied.
    End With

Shell.ShellExecute method