As one of the other posters wrote, "First, calm down". It's not the end of the world if you're not good in math. Most people do well in some others and not as well in other areas; it's very rare to find someone who does equally well in all areas of study.
Any subject can be boring when you "keep on getting the wrong answers and failing".
There are learning disabilities associated with all subjects. I had a student once who literally had to count on her fingers to add 2 and 2 and get 4, yet received very good grades in her English classes. Have you ever been evaluated for a learning disability?
You asked what you can do to try to improve your studies. You're on the right track, here's what I suggest:
- don't watch TV while you're doing your homework. You need to be able to concentrate on your homework, so getting rid of distractions is a good idea. After you've finished your homework, though, it's OK to watch TV.
- definitely keep quiet in class. Not only do you need to be quiet to hear what the teacher is saying, but, if you're talking to someone else, you're keeping that person, and others around you, from hearing the teacher.
- use your laptop wisely. You ask how you can "minimise my usage time". Just use your laptop for homework until your homework is complete, then you can surf the web, play games, etc. As far as using your laptop causing backpains, it sounds like your posture is not good. Try putting your laptop on a table or desk, instead of in your lap. Lying down to use my laptop makes my neck hurt, because I have to lift my head to see the screen. If your laptop is on a table or desk, your head can stay in a much more normal position.
- the flashcards suggested by another answerer are a good idea.
- talk to your parents and teacher (or guidance counselor) about being tested for a learning disability. One fairly common learning disability is dyslexia. When one is dyslexic, the brain "sees" thimgs out of order. For instance, "Susan is really smart" might look like "Ssuan is rellay smatr", You can learn to mentally translate this so it's correct. It's harder to "fix" "547 + 19 * 5 - 436" because there are a lot of possibilities: "745 - 5 * 91 + 643" or "574 + 59 * 1 - 364", etc.
My #1 recommendation is to talk to your parents and teacher about being tested for a learning disability.