i have lost my registration number can help to get my registration number back
Dear student!
You haven't mentioned the name of the entrance examination for which you are askiñg the question. Kindly specify that.
Let me tell you that, you must have got an email or a message when you had registered for that particular exam. Search it in your phone....you may get it. Else, visit the respective official website and contact the helpdesk. They may help you provide the registration number again.
Hope this helps.
Good luck!