Dear ayush,

as you know joint entrance exam JEE-main exam is pathway to get into several engineering college for B.tech/B.E courses.

no problem if you have not done well in your papers this year you can attempt it again next year with complete prepration. 

there will be no problem if you have attempted it 2nd time you will be easily selected in your desired college  if you do really well in your board exam JEE exam. it might just take your year away but it will not cause any major  affect to your career.

hope this helps.

best of luck...!!!