agar koi student class 12th me cbse board me fail ho gaya or usne 12th karne ke liye 12th class me hbse board le liya to uska enrollment ho jayega na

Hello Student

Really better for you to go thrugh National Institute of open School syllabus of 12 standard class after insulting with them and  the courses of 12 standard you can appear for their 12 standard exam. Otherwise you can appear as improvement candidate in all subjects through NIOS National Institute of open School system. After register with them you can appear as an improvement candidate of all subjects for 12 standard exam. There is no chance of loss and you will pass in the next year  through this system of examination.

Hope this helps.