It will open illustrator or if it is open it will minimize it or maximize it. To follow the example, create a form with two buttons, make it TopMost = true

Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
'MsgBox("minimize")
Dim startInfo As New ProcessStartInfo("illustrator.exe")
startInfo.WindowStyle = ProcessWindowStyle.Minimized
Process.Start(startInfo)
startInfo = Nothing
End Sub
Private Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button2.Click
'MsgBox("maximize")
Dim startInfo As New ProcessStartInfo("illustrator.exe")
startInfo.WindowStyle = ProcessWindowStyle.Maximized
Process.Start(startInfo)
startInfo = Nothing
End Sub
End Class