This is the Marian Antiphon for Compline essentially during Ordinary Time. According to Fr. Caswall in the 1849 Lyra Catholica, the use is somewhat more restricted, being used from Trinity Sunday to the Last Sunday
Mother of mercy, hail, O gentle Queen!
Our life, our sweetness, and our hope, all hail!
Children of Eve,
To thee we cry from our sad banishment;
To thee we send our sighs,
Weeping and mourning in this tearful vale.
Come, then, our Advocate;
Oh, turn on us those pitying eyes of thine:
And our long exile past,
Shew us at last
Jesus, of thy pure womb the fruit divine.
O Virgin Mary, mother blest!
O sweetest, gentlest, holiest!
Words: Unknown, 11th C.; tr. Fr. Edward Caswall, 1849.
Simple Tone: “Salve Regina (Simplex)” Gregorian Chant, Mode V, traditional.
Solemn Tone:“Salve Regina (Solemnis)” Gregorian Chant, Mode I, traditional
This original Latin text may be found here.