Sure! Here are the rewritten sentences:

14. She is very shy, so she doesn’t enjoy the party. → If she weren’t very shy, she would enjoy the party.
15. I will get a work permit. I will stay for another month. → If I get a work permit, I will stay for another month.
16. We won’t go out unless it stops raining. → If it stops raining, we will go out.
17. He doesn’t take any exercises. He is so unhealthy. → If he took some exercises, he wouldn’t be so unhealthy.
18. We can’t get the ticket because I don’t have the right change. → If I had the right change, we could get the ticket.
19. Study hard or you won’t pass the exam. → If you don’t study hard, you won’t pass the exam.
20. I didn’t eat lunch; I feel hungry now. → If I had eaten lunch, I wouldn’t feel hungry now.
21. I only come if they invite me. → I won’t come unless they invite me.
22. He didn’t revise all his lessons; he failed the exam. → Had he revised all his lessons, he wouldn’t have failed the exam.
23. If you arrive at the office earlier than I do, please turn on the air-conditioner. → You should turn on the air-conditioner if you arrive at the office earlier than I do.
24. The children don’t go to school in the snowy weather. → If it snowed, the children wouldn’t go to school.
25. He died so young; otherwise, he would be a famous musician by now. → Had he lived longer, he would be a famous musician by now.
26. You must tell me the whole truth or I won’t help you. → Unless you tell me the whole truth, I won’t help you.

If you need any more help, feel free to ask!