NTA organise JEE mains and Advance every year. More then 10 lakhs aspirants apply for the exam. There is no age limit, But Only those who have given there 12th Boards in Year of 2018 or 2019. Can apply for the JEE Mains 2020. So I don't think you are eligible to appear again.
Best of luck
No. Candidates who have passed class 12 or any other equivalent exam in 2019 or 2020 or those who will be appearing in class 12 or any other equivalent examination in 2020 will be eligible to appear in JEE Main 2020. Those who have passed class 12 or equivalent examination in 2017 or before and those who will appear in 2021 or later will not be eligible to appear in JEE Main 2020.
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