Accent 8 alarm. Resetting codes?

I have an ''Accenta'' intruder alarme system installed 10 years ago and recently i had power failure and the the unit will not accept our user 4-digit user code. The power on the mini unit and the key pad is as normal. Can you please advise if the unit require to be re-set and can you please provide the re-set code?

Manni Plahi
January 2010