List<string> keys = new List<string>();
            // retrieve application Cache enumerator
            IDictionaryEnumerator enumerator = HttpRuntime.Cache.GetEnumerator();
            // copy all keys that currently exist in Cache
            while (enumerator.MoveNext())
            {
                keys.Add(enumerator.Key.ToString());
            }
            // delete every key from cache
            for (int i = 0; i < keys.Count; i++)
            {
                HttpRuntime.Cache.Remove(keys[i]);
            }