Poor man's example of read/write of objects to a file, let's call it "cache", using JSON serialize/deserialize. Note that this stores the file hardcoded in ~/Data/APPNAME.cache.

CacheProvider.cs

    [Serializable]
    public static class CacheProvider
    {
        public const string CacheFilename = "APPNAME.cache";

        public static string DataStoragePath()
        {
            return Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Data");
        }

        /// <summary>
        /// Persist the cache to filesystem.
        /// </summary>
        public static void Flush<T>(T instance) where T : class
        {
            var raw = JsonConvert.SerializeObject(instance);
            var cacheFile = Path.Combine(DataStoragePath(), CacheFilename);
            File.WriteAllText(cacheFile, raw);
        }

        /// <summary>
        /// Attempts to load the cache from filesystem, or returns null if not available.
        /// </summary>
        public static T Load<T>() where T : class, new()
        {
            try
            {
                var cacheFile = Path.Combine(DataStoragePath(), CacheFilename);
                var raw = File.ReadAllText(cacheFile);
                return JsonConvert.DeserializeObject<T>(raw);
            }
            catch (Exception)
            {
                return new T();
            }

        }
    }