Hii

If I talk about Number of attempts in JEE Mains, then-

JEE Main candidates can avail 3 attempts for the national level undergraduate engineering entrance exam.

So, now you have 2 attempts left has you already given once.

All the best.

I am presuming that you have given it in 2018. Then you still can appear for it in 2019 and 2020 provided your age matches the eligibility given by the auhtorities and that you have passed your class 12th accordingly. So if you have passed class 12 in 2017 then you have only chance for 2019 and if you have passed it in 2018 then you have the last chance in 2020