xmlpersistenceprovider.cs

public override void Save<T>(T obj)
{
    string serailzedObj = SerializeHelper.Serialize(obj);
    File.WriteAllText(_PersistenceMediaPath, serailzedObj);
}

public override T Get<T>()
{
    string stringContent = File.ReadAllText(_PersistenceMediaPath);
    if (!String.IsNullOrEmpty(stringContent))
        return ((T)SerializeHelper.Deserialize(typeof(T), stringContent));
    return default(T);
}