Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As _
  System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
        Select Case Asc(e.KeyChar)
            Case 65 To 90, 97 To 122 ' A -Z : a - z
            Case Else
                e.Handled = True
        End Select
    End Sub