Sai, it depends on your highest qualification and which course you want to pursue. If your highest qualification is 10th, you can study 10+2 in regular mode or even through NIOS. NIOS candidates are eligible to appear for most entrance exams. But if your highest qualification is 10+2, though JEE has no age limit, for example if you are appearing for JEE Mains 2020, you should have passed your 12th in 2018, 2019 or should be appearing for 12th in 2020. But NEET has no such criteria. You can appear for NEET if you meet the eligibility criteria. You can also appear for CLAT because even CLAT has no eligibility criteria. So please do let us know with your highest qualification.

Hello student yes ofcourse you can continue study just get admission in nios school or state board if eligible.
You can complete your class 12 and begin your career again very easily even lots of students take drops because of their health and various issues and then they again begin their career and complete it.

Feel free to comment if you have any doubt
Good luck