If your BBM (Blackberry Messenger) contacts are lost because of any reason, and you had previously been doing backup for the BBM contacts, to make contacts be back again, what you can do is by doing Restore.
Open / run the Blackberry Messenger
(For OS V5)
Click on the Menu (BB logo

Select Options
Scroll down to enter to the Backup Management
Click the Restore
Select Restore using a backup file from device (for easier)
Select backup file (folder location : when doing backup)
There will be a notification that the contact list will be replaced .. click YES
Backup BBM Contact
See also:
Deleting BBM Chat History (Blackberry Messenger)
How to show two sheets at the same time in Ms Excel
Making Password Generator
How to make Horizontal Lines in Ms Word with easy