Rashtra Sant Tukadji Maharaj Nagpur University has a A grade from NAAC . You need your MCA certificate.
The RTMNagpur website has a registration link for the application for certificates etc. Try these links.
Have you tried an email to Deputy Registrar,Post Exam email@example.com
If both the above do not help you, then you have to visit the university administrative offices to submit the application. Be prepared with originals and copies of your relevant education/ID proof/ MCA fee receipts, hall ticket and mark cards. Have photographs and money for the DD to be paid for the certificate issuing fees.
If you are not in Nagpur, can any friend or relative visit the RTM university to find out the procedure so that you need not keep traveling up and down many times.
Lastly, whatever you submit, please keep acknowledgment slips, if you are posting documents use registered post with A/D or Speedpost.