As a childless, single, middle-aged, totally non-observant woman, am I considered a failure as a Jew? Is there any other spiritual role for a woman other than wife, mother or religious virgin? Will I end my life as a genetic dud?
Someone once said that birth is G‑d's way of showing you that you matter. Of course you are not a failure! Every person has his or her own mission and role of what he/she is meant to accomplish in this world.
The Baal Shem Tov explained that a person can live in this world for seventy or eighty years for the sole purpose of doing a good deed for his fellow. So powerful is every positive act that we do. Every good deed and every mitzvah that you do has infinite value for all eternity.
You ask what is the spiritual role for a woman other than wife or mother. The answer is that she has the same spiritual role that every person has here in this world--to develop and strengthen our relationship with G‑d by making our world a better place, a "home" for G‑d, a place where He can feel comfortable. This is the purpose, role and mission for every one of us.
How we go about doing so is as individualized as our faces. None of us is a carbon copy of each other and we each have our own unique talents and contributions to make to this world. This is true whether we are man or woman, married or single, have children or are childless, are young or old, disabled or abled. It makes no difference. We all are here to contribute!
Have you considered what contributions you would like to make to those around you? What are your special talents that you can use to increase goodness in our world? How have you strengthened your connection to G‑d today?
See here for some more food for thought on this topic.