' ** Référence : Microsoft Excel 11.0 Library Objects ou équivalent
Sub SheetProtect(ByVal sBookAProteger As String, ByVal sFeuilleAProteger As String, ByVal vPassword As Object) 
If My.Computer.FileSystem.FileExists(sBookAProteger) Then
Dim xlApp As Microsoft.Office.Interop.Excel.Application 
Dim xlBook As Microsoft.Office.Interop.Excel.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 My.Computer.FileSystem.FileExists(sBookADeproteger) Then
Dim xlApp As Microsoft.Office.Interop.Excel.Application 
Dim xlBook As Microsoft.Office.Interop.Excel.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

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

Function SheetsProtection(bProtect As Boolean, ParamArray SheetsNames() As Variant) As Boolean
    SheetsProtection = False
    
    Dim i              As Integer
    Dim ActualSheet    As String
        
    ActualSheet = ActiveSheet.Name
    On Local Error Resume Next
    
    For i = LBound(SheetsNames) To UBound(SheetsNames)
        Sheets(SheetsNames(i)).Select
        If Err.Number = 9 Then Err.Clear: Exit  Function
        If bProtect Then ActiveSheet.Protect Else ActiveSheet.Unprotect
    Next i
    Sheets(ActualSheet).Select
    SheetsProtection = True
End Function

Sub Exemple_Utilisation()
' *** Retourne  True ou False, suivant le déroulement de la fonction
'     vous pouvez mettre autant de feuilles que vous le  souhaitez
    MsgBox SheetsProtection(True, "Feuil1", "Feuil3")
    MsgBox SheetsProtection(False, "Feuil1", "Feuil3")
End Sub