In the Parable of the Lost Sheep, Jesus is explaining about a person who has been lost, or not faithful and then was found, or has repented of their sinful ways.
All text taken from the King James Bible
Luke 15:4-7 - What man of you having an hundred sheep, if he lose one of them doth not leave the ninety and nine in the wilderness, and go after that which is lost, until he find it? (5) And when he hath found it, he layeth [it] on his shoulders, rejoicing. (6) And when he cometh home, he calleth together [his] friends and neighbours, saying unto them, Rejoice with me; for I have found my sheep which was lost. (7) I say unto you that likewise joy shall be in heaven over one sinner that repenteth, more than over ninety and nine just persons which need no repentance.
Continue to read in your Bible, the story of The Prodigal Son - Luke 15:11-32. This story has two lessons ---to help you understand this story better, you will also need to read the document Famine/Hunger.Famine / Hunger