I'm not going to print out the entirety of this chapter, as it's rather lengthy. Basically, the chapter consists of two short parables that serve as preludes to the story of the Prodigal Son, which constitutes the rest of the chapter. In each case the theme, as you noted in your question, is 'lost and found.' In the parables a sheep is lost and a coin is lost. In each case the finding of what seemed lost is a cause for great joy—more loving energy than if the sheep and the coin had remained where they were 'supposed' to be. I think Jesus is affirming the spiritual Truth that nothing is ever lost in God Mind. The lost items were just where they were supposed to be, so that the experience of finding them would contribute to our collective spiritual awareness and expression.
Then comes the story of the Prodigal Son, which I think is absolutely central to the message Jesus was imparting to us all. We're familiar with the details of the first part of the story: the beloved son who takes his inheritance, wanders far from his home, squanders money on life experiences, and finds himself alone, impoverished, and forced to work at the most debasing job imaginable for a good Jewish boy—feeding pigs! Beyond the physical challenges, he feels spiritually bankrupt. He assumes that his Father must be furious at him—that by leaving home he has separated himself from his Father's love. And "when he came to himself" and realized that he could not spend his life feeding pigs, he carefully rehearses the groveling kind of plea he'll make, entreating his father to at least let him work as a hired servant.
Here, of course, comes the moment of grace. When his father sees him at a distance, he comes running to greet him. He never really hears the carefully rehearsed speech, but orders that he be robed and jeweled and shod and declares a celebration to honor his son, who "was lost and is found." Jesus' understanding of our relationship to the Father is radically different from beliefs that insist God is angry, vengeful, and demanding retribution for our 'original sin' of leaving our spiritual home to venture into this human experience. God's grace is not something that we must earn,or plead for. It is an infinite energy of love that is never lost, even when we feel most separate from it. It is God's good pleasure that we move through this human experience, learning valuable lessons so that we return to our Source with a deeper appreciation for the love and abundance available there. And sometimes 'losing' and 'finding' are important to that appreciation.