1. Get it manually from database, use some program , which decodes pass(md5 decoder) and send it via email to the user
2. When he registers, send his data to the admin, with usernames, passwords in a normal way(plain characters, not encrypted).
Well , I'm thinking not do it in that way: if he forgets pass, create new temporary, send it via email, and then user can change it.
I'm waiting for your replies