Namespace TestNs
    Public Class TestCls
        Private Sub DoSomething()
            System.Windows.Forms.MessageBox.Show("come from a private method")
        End Sub
    End Class
End Namespace

Option Strict On
Option Explicit On
Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        Dim tc As New TestCls.TestNs.TestCls
        Dim t As Type = tc.GetType
        Dim s As String = "DoSomething"
        Dim attr As Reflection.BindingFlags = Reflection.BindingFlags.NonPublic _
          Or Reflection.BindingFlags.Instance
        For Each mi As Reflection.MemberInfo In t.GetMembers(attr)
            If mi.MemberType = Reflection.MemberTypes.Method AndAlso _
              mi.Name.Equals(s) Then
                Dim i As Reflection.MethodInfo = CType(mi, _
                Reflection.MethodInfo)
                i.Invoke(tc, Reflection.BindingFlags.InvokeMethod, Nothing, _
                Nothing, Nothing)
            End If
        Next
    End Sub
End Class