@Hariom_Meena RRB gave a simple procedure to make changes. To change your application from one RRB to another, choose 'Modify Application' from the Home Page of the Registration Portal. In the second page, choose the option, 'Modify Application and apply to different RRB'.. You have to pay an Edit Fee of Rs.100/- for modifying an application made already. After successful payment of the fee, your original application will be cancelled and you can choose the new RRB to which you want to apply. A new Registration ID is generated for the new RRB. You have to return to the Home Page of the Registration Portal and login through the 'Candidate Login' link to the new RRB and complete your registration.
However this facility is no longer available. If you application status is showing Rejected, there is very less chance of getting it approved now. Please contact the concerned RRB at the earliest. Best if you can go physically there.
@shadab_akhter Registration details are sent to you via registered email id and phone. Please check your emails and sms to get the registration ID. There is no online procedure to get it back.
If you fail to find it, please please write to email@example.com. Please do not forget to provide following details like your Name, DBO, Address and other necessary information.