my rank in Jan mains is 67ooo, if I don't attempt April mains then what would be the final rank

Nutan, your All India Rabk.os calculated using the formula 100- your percentile*869010/100 where in 869010 is the no.of Candidates who appeared for January session. Let's say the no.of Candidates who appeared for JEE Mains by July is increased to 12,00,000 then your final rank is calculated by the formula 100- your percentile*1200000/100. For more information please read our article on JEE Mains 2019 final ranking: https://learn.careers360.com/engineering/how-to-calculate-rank-for-jee-mains-2019/