Format your phone/ format n70,6600,n7610,6620

Format your phone using your four fingers

format your phone by doing  step by steps procedure down here.

Reset to factory defaults (*#7780#) : Restores settings but preserves user data (photos, 3rd party apps etc)
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.

save a data first 

Steps: how to format using your fingers?

1. Switch off your phone.

2. hold down the green keypad or call  answer button

3. hold down ( * )key button .

4. hold down number ( 3 ) button.

5.turn it on and keep holding three buttons till phone ask you to enter your country, then date and time.

If you do not get prompted to enter the country and date and time, then the format has failed.
just follow the steps..

It may take a few attempts and very flexible fingers!

For the memory card, eject the memory card from the phone and connect it to PC using card reader. Format the memory card from PC.

and you can format your memory card phone using your phone by pressing format memory card..

meaning deletes everything on it, and starts it over from new, if your to do so make sure you back up whats on the memory card so you do not lose evrything.