Hello Sovit,  Up to the year 2018 , there is a limitation on number of attempt of neet exam. Open category students can give exams only for 3 times up to 25 age. But from 2018 this rule is not applicable. There is no limit on number of attempts on NEET exam. So you can attempt exam even this is your 4 th attempt. 

I hope it will help you.

Thanks. 

Hello aspirant 

Yes you can give once again in 2020 as there is no upper age limit criteria for NEET till Supreme Court passes judgment on it. However minimum age limit is 17 years. Also, you can hive maximum attempts you can. For more information you can go through this link

https://www.google.com/amp/s/medicine.careers360.com/articles/neet-eligibility-criteria/amp

Good Luck