I'm starting to get the feeling that you're asking for something that has nothing to do with the topic of this thread. If so, that would explain why you're not getting the answers you want. You need to keep each thread to a single topic and each topic to a single thread.

I think you're asking how to get your Open menu item to display a dialogue that will allow you to open a file. That is completely unrelated to the topic of this thread, which is how invoke a Button Click using the keyboard.

If that is what you're asking for then you simply need to create and display an OpenFileDialog:
vb.net Code:
  1. Using ofd As New OpenFileDialog
  2.     'Set properties here.
  3.  
  4.     If ofd.ShowDialog() = Windows.Forms.DialogResult.OK Then
  5.         'Open file here.
  6.     End If
  7. End Using