Tamil Nadu Open University

Hello Laxmi,
I have actually not understood. You were able to complete your BA based on 10th? If yes, then what's the need for doing 12th now? But if you have obtained degree from UGC approved university, then of course it remains valid.

The eligibility depends on the type of course that you wish to pursue, the details of some courses are stated below:
Diploma: Class 10th pass from a recognised board with a minimum of 40% marks.
Bachelor's degree: Class 10+2 examination with at least 50% marks.
Post-graduation degree: Bachelor's degree

Yes, from any field, if you have completed your graduation then you are eligible for this exam so you just need to prepare well to crack this exam.
All the best.

If you have completed your graduation, as one of the subject then you can apply for that.