Hii aspirants 

If you want to be a doctor. You have to work very hard. As you have mentioned you have failed in class 12 you have to give more efforts. First of all you have to class 12 exam again with atleast 50 percents marks in case of general category and 40 percent marks if you belong to sc/st/obc category. 

Also you have to qualify neet with high rank so that you get good  college for your mbbs degee.in college get good cgpa and do internship. And after completion of your course you can become a doctor. 

I hope my answer will help you out

Good luck