Convert multiple txt files in folder to csv

If they are comma delimited text files...

Sub test()
    Dim myDir As String, fn As String
    With Application.FileDialog(msoFileDialogFolderPicker)
        If .Show Then myDir = .SelectedItems(1) & "\"
    End With
    If myDir = "" Then Exit Sub
    fn = Dir(myDir & "*.txt")
    Do While fn <> ""
        Name myDir & fn As myDir & Replace(fn, ".txt", ".csv")
        fn = Dir
    Loop
End Sub