Te envié el archivo con la macro, recuerda valorar la respuesta.
Private Sub ComboBoxNOMBRE5_Change()
'Mod.Por.DAM
Application.ScreenUpdating = False
If ComboBoxNOMBRE5 = "" Then Exit Sub
Set h1 = Sheets("BASE DE DATOS CLIENTE")
Set h2 = Sheets("MODIFICAR RESERVA")
Set h3 = Sheets("BASE DE DATOS RESERVA")
f = ComboBoxNOMBRE5.ListIndex + 2
h2.Range("B4") = h1.Cells(f, "A")
h2.Range("B5") = h1.Cells(f, "B")
h2.Range("B6") = h1.Cells(f, "C")
h2.Range("D6") = h1.Cells(f, "D")
h2.Range("F4") = h1.Cells(f, "E")
h2.Range("F5") = h1.Cells(f, "F")
h2.Range("F3") = h1.Cells(f, "G")
h2.Range("A12:H20").ClearContents
Set r = h3.Columns("C")
Set b = r.Find(ComboBoxNOMBRE5, lookat:=xlWhole)
If Not b Is Nothing Then
ncell = b.Address
j = 12
Do
h2.Cells(j, "A") = h3.Cells(b.Row, "F")
h2.Cells(j, "B") = h3.Cells(b.Row, "G")
h2.Cells(j, "C") = h3.Cells(b.Row, "H")
h2.Cells(j, "D") = h3.Cells(b.Row, "I")
h2.Cells(j, "E") = h3.Cells(b.Row, "J")
h2.Cells(j, "F") = h3.Cells(b.Row, "K")
h2.Cells(j, "G") = h3.Cells(b.Row, "L")
h2.Cells(j, "H") = h3.Cells(b.Row, "M")
j = j + 1
Set b = r.FindNext(b)
Loop While Not b Is Nothing And b.Address <> ncell
End If
Application.ScreenUpdating = True
End Sub