I passed 12th in 2016 in my marksheet pass is written but actually I fail in maths I cleared this sub nios in june 2019 I preare for neet

Your gap has got nothing to do with your NEET admission. Many candidates take a break to prepare for NEET. Sometimes it might be just 1 year while sometimes its 2 years. And now there is no upper age limit to apear for NEET. So if you complete 10+2,  pass in all the subjects and secure the minimum aggregate required for your Category in Physics, Chemistry and Biology, you can seek admission if you get a Medical Seat.