First of all, I would suggest not to be so negative but in worst case it happens then you are advised to re-start your 12th again and once it is clear you are good to go for UG programs as per your eligibility and interest.

 

Good Luck!!!

"Success is not final, failure is not fatal , it is the courage to continue that counts"
Failing means now you have more time than others and more options to explore.
I would suggest you start studying for your 12th boards and complete the course as early as possible. In that way you can devote rest of your time for entrance exam you need to prepare.
Keep on studying and enjoying it
All the Best!!