P990 Soft reset Reboot

Press and hold the Power button for about 10 seconds

Master reset Sony Ericsson P990i


Use Master reset to reset your phone

Control panel -> Other -> Mater reset


Important: All user data, as well as pre-installed media
files and application data files (including, for example,
backgrounds, ringtones and pictures), will be deleted
and settings will be set to the state they were after you
selected the language. The selected local language will
be restored.

If you want to keep installed applications, unmark the
Delete user installed applications check box.

Format internal disk Sony Ericsson P990i Symbian hard reset

Switch to P990 service menu

Hold down Space key on QWERTY hard keyboard

Jog Dial Up / Press * + Jog Dial Down / Jog Dial Down / Press * + Jog Dial Down / Press *, then choose format internal disk

 

OR


If nothing works: As last resort do a Sony Ericsson phone repaire with PC Suite. Use this method to hard reset AFTER INSTALLATION----> TOOLS > PHONE REPAIR


Sony Ericsson phone repaire pc suite tools


http://www.sonyericsson.com/cws/support/softwaredownloads/detailed/pcsuite/aino?cc=gb&lc=en

Sony Ericsson  phone repaire pc suite tools


Sony Ericsson  phone repaire pc suite tools




Before you buy a new cell phone or new tablet, please try the following procedure to repair your device. First charge your battery, backup your important data if possible and in most cases take out SIM and SD card before factory reset. It is impossible to recover your data after doing a hard reset, so online backup is always important. For all of your data, a backup should be done on an external device, hard drive, raid system or media. With or without insurance, if your cell phone lost, damaged or stolen at least your invaluable data is backed up in a safe place. If you are about to sell your phone and you want to wipe your personal data, or if your phone affected with virus you have to do a hard reset. In some cases, you can delete the forgotten password or lock pattern from your device as well. All information is for devices with stock based ROMs. If you are using rooted device, always back up your EFS folder first, containing your IMEI info, etc.!