I suggest under Catholic Living— Prayer Intentions that you write another thread. There you should write what your friend is going through. And more people will respond to pray for your intention. If you haven’t prayed to God before, I suggest you do so

Just talk to Him like as you would to a father who will take care of your needs. That’s why we call Him our Heavenly Father. So yeah, just visit the other thread… as far as fasting is concerned:
Fasting
In the Old Testament and in the New Testament, there are many examples of fasting. Jesus fasted frequently. According to Tradition, fasting is encouraged especially in times of great temptation or severe trials. Certain devils, “can be cast out in no other way except by prayer and fasting”, said Jesus. (Mark 9:29)
Fasting is essential in order to achieve spiritual freedom. Through fasting, one is better able to listen to God and man and to perceive them more clearly. If, through fasting, we achieve that freedom, we will be more aware of many things. Once we are aware that we can enjoy the necessities of life without struggle, then many fears and worries fade away. We become more open to our families and to the people with whom we live and work. Our Lady recommends fasting twice a week: “Fast strictly on Wednesdays and Fridays.” (August 14, 1984)
She asks us to accept this difficult message “…with a firm will.” She asks us to “Persevere in … fasting.” (June 25, 1982)
“The best fast is on bread and water. Through fasting and prayer one can stop wars, one can suspend the natural laws of nature. Works of charity cannot replace fasting… Everyone except the sick, has to fast.” (July 21, 1982)
We have to realize the power of fasting. Fasting means to make a sacrifice to God, to offer not only our prayers, but also to make our whole being participate in sacrifice. We should fast with love, for a special intention, and to purify ourselves and the world. We should fast because we love God and want to be soldiers that offer our bodies in the battle against evil.
medjugorje.org/ol5step.htm#fasting
I encourage you to visit the prayer forum. To answer your question the religious and non-religious can fast, we are all God’s children! I’m positive He will hear your intention through fasting and prayer- He pervades our entire world… don’t lose heart for your friend.
Hope this helps!