Sub test2()
Dim p As String, ws As Worksheet, x As String, i As Integer, j As Byte, b As Boolean
p = "Lettre "
For Each ws In Worksheets
If ws.Name Like p & "*" Then
If Len(Mid(ws.Name, 8)) > Len(x) Or Mid(ws.Name, 8) > x Then x = Mid(ws.Name, 8)
End If
Next ws
If Asc(Right(x, 1)) < 90 Then
x = Mid(x, 1, (Len(x) - 1)) & Chr(Asc(Right(x, 1)) + 1)
Else
If Len(x) > 1 Then
For i = Len(x) - 1 To 1 Step -1
If Asc(Mid(x, i, 1)) < 90 Then
Mid(x, i, 1) = Chr(Asc(Mid(x, i, 1)) + 1)
For j = i + 1 To Len(x)
Mid(x, j, 1) = Chr(65)
Next j
b = True
Exit For
End If
Next i
If b = False Then
For i = 1 To Len(x) + 1
x = IIf(i = 1, Chr(65), x & Chr(65))
Next i
End If
Else
x = "AA"
End If
End If
Sheets("modele").Copy After:=Sheets(Sheets.Count)
Sheets(Sheets.Count).Name = p & x
End Sub