How Can I Get My Grades Back Up? I'm 16.?

I'm not sure how I can help because I don't know how your school's grading system works. Nonetheless, I can help you with the basics. If you're beginning a new semester, you'd have to start over. Therefore, I recommend you study hard, do all the work, and turn it in without any mistakes. If necessary, do your homework soon as you get home to make sure it's done. In case your parents don't help, you can always use the computer. Also, ask your teachers what can be done to make up for missed work, and for work that can better your grades.