Correct the faulty sentence in written form

Correct the faulty sentence in written form.
1. There isn’t anything which can go wrong with the machine
2. My daughter, which is 16, goes to school.
3. I was disappointing with the results of the exams.
4. Suffering from depression himself as a teenager, Kevin could understand how his son was feeling.
5. I used to take part in a competition once.
6. I would have long blond hair when I was young.