sir for the past teo days we are trying to register for NATA 2020 examination.. but we are unable to register as we are getting the "please enter valid password".. we tried several times by changing the passwords..please help us fix this issue

Have you entered the correct password if you are changed several time. Try once again if it persists then the other option you have is that try to re register with other email id. There may be issue so with new email id there won't be any problem. It may be due to technical problem . So it won't affect with re registration from other email id.