It may happens that a program corrupts the C: drive of your phone. In such case, some data can be lost of course but, more annoying, some applications may not work or work only partially,...
On a Series 60 based phone, two key sequences will allow to restore your phone to a cleaner state:
Normal Reset (*#7780#) : Restores ini files from rom but preserves user data (photos, 3rd party apps etc)
Deep Reset (*#7370#) : This reformats completely the C: drive. All applications and files stored on this drive will be lost and clean default files will be rewritten.
In both case, the phone will ask you a confirmation and you will have to enter a security code (12345 by default).
Files and applications stored on E: drive are not be affected by these sequences.
Note : Full phone formatting a 6600! Here to let everybody how to perform a Full phone formatting on a 6600! If you encounter situation like below on your 6600, 1. Blank screen phone unable to reboot. 2. Phone only able to boot-up to "Nokia" word screen. 3. Install some program but not able to uninstall it after that. 4. Unable to delete unwanted files on C drive. Do a Full phone formatting on your 6600! as steps below, 1. Make sure you have at least 3/4 charge of battery power left. 2. Backup your contacts list and personal files to MMC memory card. 3. Switch-off your 6600 phone and REMOVE UR MMC!. 4. Press and hold 3 keys; Green dial key, * Star key, no. 3 key on keypad and then press the power on/off to swtich on the 6600 phone. Remember, do not let go the 3 press and hold keys until you see a formatting word screen show! 5. After a few minutes when the Full phone formatting completed, your 6600 will back to original system and factory settting[/b][/b]
[stick by lovekonadj]