Class 12-science

You can do many things such as -
start your own business (for your information most successful businessman are less qualified than you).
continue studying (I recommend that you exercise this option) - If you want to study, please refer my answer to this post.If I got low marks in 12th less than 60% where should I go?
look for a job - search internet, I am sure you will find something
any combination of the above options: like (1 and 2), or (2 and 3) or (1 and 3).
All the best.
Do well in life (this is not the same as scoring well).

You can prepare for Engineering entrance exams like JEE, BITSAT, ICAR, IPU-CET and others and score well in them to get into a good Engineering college and pursue your B.tech from there.
Or you can join B.sc in any government college and go for research and teaching as your career options.
There are other options but these are the broader options that people go for.

Engineering. Engineering is one of the sought after career by science students.
Architecture. Bachelor of Architecture (B. Arch) Five years course.
Merchant Navy.
Commercial Pilot.
Bachelor of Science.
National Defense Services-Indian Navy Officer, Indian Air Force.
Railway Apprentice Exam.
Arts and Humanities.

Do pursue higher studies.
If you are really interested in Physics and Biology but unable to take up the same subjects for your +2 in your current school, then I suggest you to change your school to take the stream of your choice for your further studies.
Sticking to these subjects plus chemistry, you can put your heart and try for Medical Colleges. Otherwise, you can also go for undergraduate in Basic Sciences.
Life is full of opportunity and it's never too late to make amends. Try working hard and once you are through, there will be plethora of opportunities.
DM me if you have further queries.
All the best.

Do pursue higher studies.
If you are really interested in Physics and Biology but unable to take up the same subjects for your +2 in your current school, then I suggest you to change your school to take the stream of your choice for your further studies.
Sticking to these subjects plus chemistry, you can put your heart and try for Medical Colleges. Otherwise, you can also go for undergraduate in Basic Sciences.
Life is full of opportunity and it's never too late to make amends. Try working hard and once you are through, there will be plethora of opportunities.
DM me if you have further queries.

If you are not able to appear in engineering exams, then many forms are available in the market to fill up & give the entrance exams like NDA, Merchant Navy.
There are some engineering colleges are in India that gives the facility of direct admission. You can also choice this option.

If you are not able to appear in engineering exams, then many forms are available in the market to fill up & give the entrance exams like NDA, Merchant Navy.
There are some engineering colleges are in India that gives the facility of direct admission. You can also choice this option.

Diploma holders in engineering and BSc are only eligible to seek lateral entry admission in B.Tech 2nd year. You are not eligible to seek admission in 2nd year of engineering based on your 10+2 educational qualification.