Good morning ,

I hope you are fine. If you are fail in your class 12th board exam then yes you have to give the exams next year for clearing your boards. Without clearing your boards you cannot do further studies. If you are fail in one exam then you can give compartment exam but if you will fail in all the subjects then you have to repeat your class. So , yes you have to attend your school. Don't panic work hard.

I hope this will be helpful for you.

Good wishes !!