Hii aspirant
Hope you are doing well amid covid-19 pandemic
If you are not able to Login in Tancet 2020 i.e Anna. University official website
Then you can refresh the page and try again if failing to do so you should check your credentials if even they are right you can contact the support team of university they will fix the issue and you will be able to login
For your convenience I'm sharing this link of Anna University through which you can contact support team
https://www.annauniv.edu/ipr/contact.php
If your problem does not get solved go through this link
https://cfr.annauniv.edu/annasup/help.php
Hope it helps