Sure! Here are the sentences rewritten:

1. "I lost my new bike this morning," the boy informed his parents.

2. "You didn't follow the instructions I gave you yesterday," the instructor remarked.

3. "Alright, I’ll be honest with you now," James said.

4. "You need to practice for two hours every day!" (As my piano teacher suggests).

5. The driver stopped to buy some cigarettes.

6. The police arrived too late, so the robber managed to escape.

7. We anticipate that the government will suggest modifications to the taxation system.

8. His parents kept him at home to complete his assignments.

9. "Please don't leave these books on the table," the librarian advised the students.

10. "Who has written this note?" the boss inquired of the secretary.

11. "I just received a postcard from my sister," my friend mentioned to me.

12. My friend stated, "Don't leave until I call you."

13. He regretted not inviting him to his birthday party.

14. "I am writing this letter to you at Mr. Foster's request."

15. Mastering a new language requires time and patience.