Here are the completed sentences in reported speech:

1. "Be careful!" she told me.
→ She told me to be careful.

2. "Don't wait for me if I'm late," she told me.
→ She told me not to wait for her if she was late.

3. "Please slow down!" she said.
→ She asked me to please slow down.

4. "Hurry up!" she said.
→ She told me to hurry up.

5. "Don't go out at night," she warned us.
→ She warned us not to go out at night.

6. "Don't touch these buttons," the man said.
→ He warned us not to touch those buttons.

7. "Please don't tell anyone what happened," she said.
→ She told me not to tell anyone what happened.

8. "Stay in bed for a few days," she advised me.
→ She advised me to stay in bed for a few days.

9. "Turn on the light, please, Nam," she said.
→ She told Nam to turn on the light.

10. "Don't use my phone," she told me.
→ She told me not to use her phone.

11. "Don't play games so much, boys," she said.
→ She told the boys not to play games so much.

12. "Don't watch TV so much, John," she said.
→ She advised John not to watch TV so much.

13. "Help your friends," she told me.
→ She told me to help my friends.

14. "Don't eat in the class," she advised us.
→ She advised us not to eat in the class.

15. "Don't be so lazy," she told us.
→ She told us not to be so lazy.

16. "Don't write on the wall, boys," she said.
→ She asked boys not to write on the wall.

17. "Try your best for the final examination," she advised.
→ She advised us to try our best for the final examination.

18. "Practice English more and more," she told us.
→ She advised us to practice English more and more.

19. "Be confident," she told us.
→ She told us to be confident.

20. "Don't worry about the exam," he said.
→ He told us not to worry about the exam.