Ответ:
1. My friend told me that he/she had been in Africa the previous year.
2. My sister said that she had had a good rest in summer.
3. The children said that they were going to the party the following day.
4. Father said that he had found a new job.
5. The teacher said that he/she didn't like his/her students cheating.
6. My friend asked me if I like soap.
7. Mother asked me if I would shopping with her.
8. The teacher asked her students if they had written their essay.
9. Mother asked me if my friend was sleeping then.
10. Granny asked my sister if she had bought bread.
11. My friend asked me where I was going.
12. Mary asked me when I got up.
13. Mother asked me when I had saw my sister last .
14. Mother asked father when he would fix the lock.
15. Me friend asked me why I hadn't helped him/her.
Объяснение:
https://speakasap.com/ru/en-ru/grammar/nepryamaya-rech/
Хорошая статья про косвенную речь. Написано как основная информация, так и некоторые углубления в тему.