As you are telling that you are failed in 3 subjects . You have two option now, Firstly you can go for re-appear next year (in which you have to give these subjects paper only)

Secondly, You can go for taking admission again in 12th and work hard and getting a good percentage ( in my opinion this will be good for your percentage because as you are giving your one year again to the 12th class it will be benificial for your future).

All the best