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 your security code (12345 by default). In all cases make sure you have at least 3/4 charge of battery power left
Files and applications stored on E: drive are not be affected by these sequences
Useful help: Full phone formatting a phone!
Here to let everyone know how to perform a FULL phone formatting on a 6600! If you encounter situation like below on your phone,
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 phone! 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
4. Press and hold 3 keys; Green dial key, * Star key, no. 3 key on keypad and then press the power on/off to switch 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 phone will back to original system and factory setting.