Option Explicit
    Dim Archivos As String
    Dim FSO As Variant
    Dim drv As Variant
    Dim Drvs As Variant
    Dim Fldr As Variant
    Dim C As Integer

Private Sub Form_Load()

    Set FSO = CreateObject("Scripting.FileSystemObject")
    Set Drvs = FSO.Drives
    C = 0
    
    For Each drv In Drvs
    
        If (drv.DriveType = 2) Or (drv.DriveType = 3) Then
        
            Set Fldr = FSO.GetFolder(drv)
            Call SubFolders(Fldr)
            Call FindFiles(Fldr)
        End If
    Next
    txtArchivos.Text = Archivos

End Sub
    

Sub FindFiles(ByVal Folder As Variant)

    Dim fls As Variant
    Dim fl As Variant
    
    Set fls = Folder.Files
    For Each fl In fls
        C = C + 1
        Archivos = Archivos & CStr(C) & ".  " & CStr(fl.Name) & vbCrLf
        
        'SI QUIERES MANDARLO A UN ARCHIVO DE TEXTO
        'Set Ar = Fso.createTextFile("C:\Archivos.txt")
        'Ar.write (Archivos)
        'Ar.Close
        
    Next
End Sub

Sub SubFolders(Folder As Variant)

    Dim Fldrs As Variant
    Dim Fld As Variant

    Set Fldrs = Folder.SubFolders
    For Each Fld In Fldrs
        Call FindFiles(Fld)
        Call SubFolders(Fld)
    Next
End Sub