Another lazy parent using a fake illness to avoid being a good parent. There is NO such thing what so ever as ADD or ADHD.
Your child won't talk to other because you don't make her talk to others. If they ignore her and won't give her anything then she will be forced to talk to them.
Most kids have a hard time focusing in school. Since there's no such thing as ADD and ADHD, its simple boredom. Most kids don't want to do boring school work and rather be playing. Can't blame them. Not to mention most the things in school a child never even needs
She will get worse since you rather label it something that is not even real rather then be a PARENT and under stand why she does that. Make her talk to others, make her do her school work and if she won't, then let her fail and be held back.
Cut out all the junk food and fast food in her diet, no computer, no TV, no electronics at all. Kids that grow up around electronics and become distant