public static class ObservableExtension

     {

         public static void Sort<TSource, TKey>(this Collection<TSource> source, Func<TSource, TKey> keySelector)

         {

             List<TSource> sortedList = source.OrderBy(keySelector).ToList();

             source.Clear();

             foreach (var sortedItem in sortedList)

                 source.Add(sortedItem);

         }

         public static void Sort<T>(this ObservableCollection<T> collection) where T : IComparable

         {

             List<T> sortedList = collection.OrderBy(x => x).ToList();

             for(int i = ;i<sortedList.Count();i++)

             {

                 collection.Move(collection.IndexOf(sortedList[i]), i);

             }

         }

     }