Candidates will get 2 mails from RRB official board after successful registration
1st Mail all about the registration process is completed successfully and other one contains the registration number and other important details.
So, candidates are advised to recall the registered mail id to check the emails. If you found emails from RRB official board in your Inbox you can get Registration number and other important details from there.
Write to (firstname.lastname@example.org) email id. Write a mail to that email id regarding lost of registration number.