UPDATE - Please note that the updated post on this topic is here. So if the below given method does not work for you, refer to the new tutorial.
WARNING: Phone flashing is a double-edged sword; it may be useful and dangerous at the same time. It may brick/damage your phone for good (if not done carefully), so please DO NOT flash your device if you don’t know what the hell flashing a phone means
In this post I will explain the use of Phoenix (Nokia Service Software) to flash a normal (not dead) Nokia mobile (taking Nokia N8 as an example). Flashing means re-installing phones firmware (Operating system) files. There are many situations when it becomes necessary to flash a mobile deletion/corruption of system files, phone is dead/bricked