if any student failed in retest in 2 subjects in 2020 12th board... n he is going to appear in 2021 march for 2 subjects in which he failed... has to give only 2 subject exam for BAMS N BHMS or has to give all subjects exam... neet is required for BAMS n BHMS

NEET is the entrance examination for admission to MBBS,BDS, Ayush and Veterinary courses across India. And BAMS and BHMS are also a branch of Ayush Courses. So to answer your question, to pursue BAMS and BHMS, NEET is mandatory and NEET eligibility criteria also applies for BNYS. So to be eligible for NEET, you should have completed your 12th, passed in all subjects and secure a minimum aggregate of 50% in Physics, Chemistry and Biology. It is 50% for General Category, 45% for PWD and 40% for OBC,SC,ST. Now if you belong to OBC Category, the Category you belong to should be also listed in the Central OBC list. Or else you will be considered as General Category and so you have to secure a minimum aggregate of 50% in Physics, Chemistry and Biology. This 50% is inclusive of the Theory and Practical marks scored in Physics, Chemistry and Biology collectively. You needn't score 50% in Physics, 50% in Chemistry and 50% in Biology separately. You need an aggregate of 50% or 40% depending on your Category as an aggregate in Physics, Chemistry and Biology. And along with Physics, Chemistry and Biology, you should also have studied English as one of the core subjects in your 12th. You can just appear for those 2 subjects, clear them and secure the aggregate required and you will be eligible for NEET 2021.