If you are giving exam through your school then you can just contact your school

And tell them that you want to give that particular subject in the month of the March if anyhow it is possible they will arrange that

They will fill the form and u will appear in exam

but if not you get another chance in the month of june again the compartment exam will happen.

Do well this time

Don't worry u get enough chances to clear your 12th just make the most of it

Do your best!!!