Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

 Dim files = From file In My.Computer.FileSystem.GetFiles(Application.StartupPath) Order By file Ascending

Dim i As Integer

For i = 0 To files.Count - 1

            ListBox1.Items.Add(files(i))

Next

End Sub