Unfortunately not. According to the criteria of JEE Main, a candidate is only eligible if he/she has passed the class XIIth board for the first time within 3 years of passing out. For example, if you have cleared class XII board exams for the first time in 2015, then you can give JEE Main only in 2015, 2016 and 2017, you can give JEE Advanced only in 2015 and 2016 as JEE Advanced requires to give exam within 2 years of passing out. So, according to this, you cannot legally give JEE Main now.

All the best!