You say that you pray but without any result, and that you have a feeling of being in a void. I will give you a very simple but very efficient method.
When you pray, start by imagining a multitude of spirits scattered around the whole world, concentrating on the Creator from where they are, uniting with him through their thought and love. Imagine that you are joining with these beings so as to pray with them.
Your voice is not isolated in the wilderness of life, as you are soliciting heaven together with thousands of light beings.
You will then feel that your prayer has been heard because of the large number of beings wanting to be heard, and you will also benefit from it.
It is because you pray alone that you have the feeling your prayer is not reaching its goal.
The secret is to unite with all those who pray, since at every moment, somewhere in the world, there are beings praying.