Purpose and thrust (H-J Kraus, PSALMS 60 - 150)

from 1993 edition (Fortress Press) -- volume was translated by Oswald C. Hilton:
The meaning of Psalm 77 is, first, that here a petitioner suffers with his whole life from the rejection of the people under God's judgment.  All his thoughts and senses center on Israel.  The community of God is the supporting basis and the focal point of his existence.  With difficulty and without comfort the petitioner, who longs for certainty and healing, must bear God's absence, Yahweh's hiddenness.
A change takes place in the psalm when he who laments resolves to recall the wondrous deeds of God on behalf of his people (verses 11 - 15).  The confession that all God's ways are holy (verse 13) emerges, not from the consciousness of separation rom the deus absconditus, but from the encounter with the great wonders and works of the deus revelatus.  The greatness and incomprehensibility, the majesty and uniqueness of the God of Israel are now first recognized.  Thus the praising absorption in the salvific event turns into the comfort that overcomes all affliction.  In view of the wonders that God has done, the salvific faithfulness of God can no longer be subject to doubt.  Yet holiness is that perfection which basically determines all conduct of God over against Israel.  Being near "without footprints" (verse 19) -- without the visible proofs of his coming -- that is God's way of dealing with his people.  All the creative miracles (verses 16 - 20) take place under this signature.