only 3 to 4 months are left to study and i haven’t studied much....i am confused wheather i revise whatever was taught earlier aur should i just focus on whatever i am studying now....
what should i do ?

If you haven’t study much till this point you can focus only on class 12^thportion because the weightage of the topics from class 12^thare more and it is fresh which will help you to get a proper hold on the topics.You need to make sure that whatever you are doing , it is of good quality and that you can get marks on those topics. Don’t go after covering as much topics as possible that will reduce the quality of coverage because of lesstime available.