I always have backlogs in every semester, which includes 5 out of 12 in my BA. What should I do?

You have to concentrate on your studies. If you can't, then you have to build up your concentration power by doing meditation, and when you study just take a break of 5 min -10 min. after every 45 min. Thus, will help you a lot to remember you each and every thing which you studied.