Bonjour,
Une seule petite modification :
Private Sub btnModifier_Click()
' Lire et Modifier le contenu des lignes
Dim i As Integer
Dim R As Variant
R = MsgBox("vouler vous confirmer la modification", vbYesNo, "Valider ")
If R = vbNo Then Exit Sub
For i = 4 To Feuil2.Cells(Rows.Count, 1).End(xlUp).Row
If N_Item.Caption = Cells(i, 1) Then
Cells(i, 2) = ComboBox1.Text
Cells(i, 3) = ComboBox2.Text
Cells(i, 4) = ComboBox3.Text
Cells(i, 5) = TextBox1.Text
Cells(i, 6) = TextBox2.Text
'''INSTRUCTION MODIFIEE''''''''''''''''''''''''''''''''''''''''''''''
Cells(i, 7) = Format(CDate(TextBox3.Text), "dd/mm/yyyy")
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
MsgBox " confirmer de la modification"
End If
Next i
Unload Me
UserForms.Add(Userform_name).Show 0
End Sub
En espèrant que cela t'aide