One possible version:
My mother got along well with all our new neighbours except the man who lived next door. My mother said he didn’t look like a nice man.
One day, when my mother came home from work, she realized that she had lost her new necklace which she had bought the day before. She was very worried. She wondered where she had been just then. She thought that perhaps the man who lived next door had stolen her necklace. We planned to call the police at once. Just then, someone was knocking at the door. It was the young man, our new neighbour. I was shocked that my mother’s necklace was in his hand. He told us that he found it at the doorway. And he thought it must be my mother’s. so he came to return it.
Yes, that’s true. It is the necklace my mother lost. My mother was very thankful. She told our new neighbour that we could be good friends later.