Don't worry, keep opening the website, and trying again. There might be a server error because alot of people are simulateously trying to log on to the site.

Dear Student
The correction window is now open please visit the link given below:
https://cbseneet.nic.in/cbseneet/online/CandidateLogin.aspx

Dear... correction time schedule has been changed. It will commence from 15th March 2018 from10 am. You will be allowed once to correct your details. CBSE will allow correction until 17th March, 2018. Don't worry. Do it within specified time duration. All the best !

Dear student

greetings

the online correction portal for neet will begin from 15th March 2018, 10 AM to 17th March 2018, 11:50 PM. Kindly do not panic you have time to correct between 15th to 17th March.

for any other kind of information do comment below.