Sub SheetProtect(ByVal sBookAProteger As String, ByVal sFeuilleAProteger As String, ByVal vPassword As Object) 
If Dir(sBookAProteger) <> "" Then
Dim xlApp As Excel.Application 
Dim xlBook As Workbook
Dim i As Integer

xlApp = CreateObject("Excel.Application") 
xlBook = xlApp.Workbooks.Open(sBookAProteger)
For i = 1 To xlBook.Sheets.Count 
If xlBook.Sheets(i).Name = sFeuilleAProteger Then

xlBook.Activate()

xlBook.Sheets(sFeuilleAProteger).Select()

xlBook.Worksheets(sFeuilleAProteger).Protect(vPassword)

Exit For

ElseIf i = xlBook.Sheets.Count Then
MsgBox("La feuille à protéger n'existe pas!", vbCritical) 
End If
Next ixlBook.Close(True) 
xlApp.Quit()

xlBook = Nothing

xlApp = Nothing

Else
MsgBox("Le fichier n'existe pas, vérifier le chemin !", vbCritical) 
End If

End Sub
Sub SheetUnprotect(ByVal sBookADeproteger As String, ByVal sFeuilleADeproteger As String, ByVal vPassword As Object) 
If Dir(sBookADeproteger) <> "" Then
Dim xlApp As Excel.Application 
Dim xlBook As Workbook
Dim i As Integer

xlApp = CreateObject("Excel.Application") 
xlBook = xlApp.Workbooks.Open(sBookADeproteger)
For i = 1 To xlBook.Sheets.Count 
If xlBook.Sheets(i).Name = sFeuilleADeproteger Then

xlBook.Activate()

xlBook.Sheets(sFeuilleADeproteger).Select()

xlBook.Worksheets(sFeuilleADeproteger).Unprotect(vPassword)

Exit For

ElseIf i = xlBook.Sheets.Count Then
MsgBox("La feuille à déprotéger n'existe pas!", vbCritical) 
End If
Next ixlBook.Close(True) 
xlApp.Quit()

xlBook = Nothing

xlApp = Nothing

Else
MsgBox("Le fichier n'existe pas, vérifier le chemin !", vbCritical) 
End If

End Sub
'Exemple d'utilisation
Private Sub Button1__Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click 
'Protéger
Call SheetProtect("C:\Classeur1.xls", "Feuil2", 1206) 
'Déprotéger
Call SheetUnprotect("C:\Classeur1.xls", "Feuil2", 1206) 
End Sub