i had done 12th with 53% but it is less ,can i again give exam for i2th. i do not have all my certificate because i am doing diploma

sure you can give it again. however it makes sense only if your performance was hampered seriously due to external factors like sickness etc. Otherwise you must re-assess yourself. Try to find what is your aptitude, since it seems that your current subjects are unable to get your attention. Wish you

Yes you can, if you just did it in 2012, you can fill forms for 'improvement examinations' or if it has been more time since you did 12th then you can do it from National Institute of Open Schooling(NIOS). As you have already passed 12th, you can opt for on demand exams of NIOS which happen every mo