Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean) 
     
    If ActiveSheet.Name = "Sheet1" Then 
        On Error Resume Next 
         'Resume to next line if any error occurs
        Dim Cell As Range 
        With ActiveSheet 
             'first of all unprotect the entire
             'sheet and unlock all cells
            .Unprotect Password:="123" 
            .Cells.Locked = False 
             'Now search for non blank cells
             'and lock them and unlock blank cells
            For Each Cell In ActiveSheet.UsedRange 
                If Cell.Value = "123" Then 
                    Cell.Locked = False 
                Else 
                    Cell.Locked = True 
                End If 
            Next Cell 
            .Protect Password:="123" 
             'Protect with blank password, you can change it
        End With 
        Exit Sub 
    End If 
End Sub 



Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean) 
    On Error Resume Next 
     'Resume to next line if any error occurs
    Dim Cell As Range 
    With ActiveSheet 
         'first of all unprotect the entire
         'sheet and unlock all cells
        .Unprotect Password:="123" 
        .Cells.Locked = False 
         'Now search for non blank cells
         'and lock them and unlock blank cells
        For Each Cell In ActiveSheet.UsedRange 
            If Cell.Value = "123" Then 
                Cell.Locked = False 
            Else 
                Cell.Locked = True 
            End If 
        Next Cell 
        .Protect Password:="123" 
         'Protect with blank password, you can change it
    End With 
    Exit Sub 
End Sub