Powerful prayer to St Monica for conversion of heart

Circle of Pedro Berruguete

For those of us grappling with the vexing problem of our loved ones who have lost faith in Our Lord, please consider praying to St Monica, mother of St Augustine of Hippo - a Doctor of the Church (354–430 AD). St Monica is the patron saint of wives, difficult marriages, widows, mothers, disappointing or wayward children, and victims of adultery and abuse. 

Novena to St Monica

https://www.stritascentre.org/novena-prayer-to-st-monica-and-st-augustine-1

Prayer to St Monica

Blessed Monica, mother of St. Augustine,
we give thanks to our Father in Heaven
Who looked with mercy upon your tears over your wayward son.
His conversion and heroic sanctification were the fruit of your prayers.
Dear St. Monica,
we now ask you to pray with us for all those sons and daughters
that have wandered away from God,
and to add your prayers to those of all mothers
who are worried about their children.
Pray also for us that, following your example, we may,
in the company of our children,
one day enjoy the eternal vision of our Father in Heaven.
Amen.

Brief Story of Saint Monica

Saint Monica (322–387 AD) was raised in a Christian home in Tagaste, North Africa. She was given in marriage to a pagan Roman man named Patricius, who while not an entirely bad man, was a wayward man with a violent temper; Monica had to endure this daily as well as live with his ill-tempered mother.
She eventually became a deeply devout woman. Monica suffered greatly and fervently prayed for long years for the conversion of her family members. Her patience and kindness became a source of encouragement to other unhappy housewives with whom she came in contact. Monica gave birth to three children and was greatly distressed that her husband would not allow them to be baptized.
Her eldest son, Augustine, was the most wayward of her children and caused her the most pain, and for his conversion, she prayed fervently for years. Through her persistence in prayer and good example, her husband became a Christian shortly before his death.
When Augustine, caught up with Manichaeism, a heretical sect, moved to Milan, Saint Monica followed him, where she became friends with the Bishop of Milan, Saint Ambrose, who eventually led the wayward Augustine to convert to the Christian faith. 
The holy bishop St. Ambrose comforted Monica, saying, “The son of these tears of yours shall not perish!”
Augustine was baptized shortly before her death, but not before they had spent peace-filled, joyous days together, discussing the mysteries of God, whom they loved so much.