If you remember your username hit your bis type it in and hit lost password. You can have one "blackberry" email per phone but you can have multiple other accounts
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Did you actually set up you BIS account to create you email, or did you set up your email directly on your phone without using BIS?
If you were not directly prompted to set up your BIS info on your phone through the email setup, you have yet to set it up and can still do so. It will tell you that there is a PIN associated with the account because there is, but it hasnt been set up yet.
Go into your email set up and create your BIS account. You should be good to go from there.