I need a hint on how should I get a good grades and I have tried everything I am sure:confused::confused::confused::(:(:(

A few ideas:

*if you have a friend who does well, ask them to help you study
*see if the school has any tutors or volunteers who will work with you before or after school
*figure out what helps you retain information better... for some it is complete quiet while working, for others it may by having some music on in the background.
*might help breaking a subject down into smaller chunks... for example, study 15-20 minutes each night of the week before a test on Friday instead of trying to do it for an hour just the night before.
*take good notes... ask classmates or friends to share theirs with you (make sure you actually review them!! )
*ask the teacher if they can give you a heads up on what the next lesson topics will be so that you can get a jump start on them at home
*ask the teacher if there is another way something can be explained... math, for example, will often have different ways of coming to the same answer. One way may "click" better for you than another
*maybe your parents can look into outside tutoring help... sometimes you will find teachers who will provide tutoring after school for additional income