Sub Convertir()
Dim tablo, i&, t, s
With Feuil1 'CodeName, à adapter
tablo = .[A1].CurrentRegion.Resize(, 2) 'matrice, plus rapide, au moins 2 éléments
For i = 1 To UBound(tablo)
t = Trim(Replace(Replace(t, "AM", ""), "PM", ""))
s = Split(t, "/")
If UBound(s) = 2 Then t = s(1) & "/" & s(0) & "/" & s(2)
If IsDate(t) Then tablo(i, 1) = CDate(t)
Next
'---restitution---
If .FilterMode Then .ShowAllData 'si la feuille est filtrée
.[A1].Resize(UBound(tablo)) = tablo
End With
End Sub