If you have lost your registration number then you can find it on the registration certificate or your admit card for any of the examination. But if you are asking that you have lost the registration certificate then you have to file a complaint of losing document in the nearest PS and have to take the receipt copy of complaint to your college. The officials will guide you out further. The process is quite simple and you can expect to get a duplicate copy of your Registration certificate from the council in 2-3 months of time.

To know more about BEd visit the link below:

https://www.careers360.com/courses/b-ed-bachelor-of-education

I hope this answer helps. All the very best for your future endeavors!