Try to understand the reasons for your daughters nervousness and also look at your own attitudes in dealing with her. If there is too much pressure to perform a child may feel nervous.
Help her learn relaxation techniques such as deep abdominal breathing. Take the help of a psychologist or counselor for the same. Yoga and pranayam also help.
Weaning a child away from too much TV needs an effort on the part of elders to first control their own TV viewing time, as well as enforcement of limits which can be arrived at after mutual discussion as to how much time per day can be spent on TV and which programs can be watched.