I think I have a learning disability. I am 14 years old in grade 9 and ever since I can remember I have had trouble taking things in at school.
I cannot concentrate in maths, english and social studies. When any teacher is talking and writing on the board I try so hard to concentrate. But I cant, its like everything their saying/writing is going in one ear and out the other. I have tried taking notes but it just confuses me because I'm consentrating more on writing and not what the teacher is saying. Please help.

Ask to be tested - the school should have people on staff or could refer you to someone outside of school.

What do your parents say about this?

Ask your parents to have you tested. Its something that can't be done over the internet but it sounds like you have some kind of problem. It may be as simple as a different approach and not a disability at all.

Everyone has a different way of learning, but it can be broken down into 3 sections.

Doing.
Seeing.
Hearing.

I agree with other posters to get tested to rule out a learning disability, and ask about learning styles for you and which one you could be, with that information you can learn whatever you want by adapting your learning style to what's being taught in the classroom.