I am in class 12th maths stream in rajasthan board after this what I will do ?I worried about my future
You don't have to worry you just need to decide a future that you want and there are numerous options for you after 12th. If you are interested in engineering then you can prepare engineering entrance exams, if you are interested in medical then you can prepare for medical entrance exams.
If you are not interested in these fields then you can choose courses like BCA, BBA, Hotel Management, B.Com, B.Sc etc. If you want to work for government sectors then you can do graduation in any stream and then prepare for exams like Banking, SSC, Railways, UPSC etc. Ask yourself where do you want to see yourself in 5-8 years, what really excites you to study and what kind of career you want and then decide accordingly.
I hope this helps.