How can i format my sony ericsson z550i

To master reset your phone Z550i, go to Settings> General > Master reset > Select Reset settings to delete your changes to settings or Reset all to delete your changes to settings, all contacts, messages, personal data, and content you have downloaded, received or edited. Then press continue.
Hope this helps!

it's 0000 by default

0000 use this its default reset code

default code is 0000

In the settings, you'll find something called Master Reset. This will erase all data whatsoever on your phone and reset it to its factory state. Try and tell me if it doesnt work

you may have some viruses on your phone.
i also had the same problem,u can format your phone/memory card or u can use an anti virus!!!!!!!!!!!!!!

What is this Virus doing to your phone?

how to format z550i sony ericsson

Connect the phone to your computer using a usb cable or card reader.. If you connect the phone there will be 2 extra drives in my computer. Right click on the memory card and click on format. Also choose the FAT32 file system while formatting it is more reilable. If you want to do this from a card reader a new USB drive will be shown in my computer. Right-click and format.

First of all backup ur every important thing.Switch off ur phone hold *,3 and green call button at the same time and switch on ur phone.problem resolved.

Regards,
Sandeep Singh