Here is an excerpt from E.M. Bounds on Prayer, that illustrates that God Does Not Disappoint Us:
Prayer is mighty in its operations, and God never disappoints those who put their trust and confidence in him. They may have to wait long for the answer, and they may not live to see it, but the prayer of faith never misses its object.
"A friend of mine in Cincinnati had preached his sermon and sank back in his chair, when he felt impelled to make another appear," says Dr. J. Wilbur Chapman.
A boy at the back of the church lifted his hand. My friend left the pulpit and went down to him, and said, "Tell me about yourself." The boy said, "I live in New York. I am a prodigal. I have disgraced my father's name and broken my mother's heart. I ran away and told them I would never come back until I became a Christian or they brought me home dead." That night there went from Cincinnati a letter telling his father and mother than their boy had turned to God.
Let's keep on praying for our prodigals until our last breath!
….And we rejoice in the hope of the glory of God. Not only so, but we also rejoice in our sufferings, because we know that suffering produces perseverance; perseverance, character; and charter, hope. And hope does not disappoint us, because God has poured out his love into our hearts by the Holy Spirit, whom he has given us. Romans 5:2-5, NIV