Default desire 500 - all cities lost

Hi everybody,

Trying to apply a modified update in my desire 500, something went wrong and now, my city list is totally empty.
This affects actually the weather & the clock application.
By empty, I mean that I try to add a city, but there aren't any. I believe that somehow, the related database was corrupted. I searched other forums for this, tried many different ways to restore or to find the db and somehow fix it, but no luck. Can somebody assist ?