Format

Power phone off.

Press down (and keep pressed) the '3' key + the '*' key + the green "talk" key (all three).

Power phone on (while above three keys are pressed down).

When the phone says "formatting", you can release.

Do only with full battery or on AC.

All data will be gone/reset after the formatting is complete.

See this thread for more info:

http://www.allaboutsymbian.com/forum/showthread.php?s=&threadid=17507

You can also "reset" to factoty settings by using: *#7780# (so you don't loose your installed apps)

More/all Codes for Nokia 6600 youll find here (german site),removed