Favorite Prayer of Many Saints that is Often Attributed to St. Bernard - The Memorare to the Blessed Virgin Mary
Saint Mother Theresa would say this as an "Express" Novena 10 x in a row whenever in great need.
The Memorare Prayer:
Remember, O most gracious Virgin Mary, that never was it known that anyone who fled to thy protection, implored thy help or sought thy intercession was left unaided. Inspired by this confidence, I fly unto thee, O Virgin of virgins, my Mother. To thee do I come, before thee I stand, sinful and sorrowful. O Mother of the Word Incarnate, despise not my petitions, but in thy mercy hear and answer me. Amen.