by Hard Reset
the hard reset the phone will reinstall the software included.
Note: Backup the files that you want to keep, before you perform a hard reset. You can backup files via a computer or a memory card.
firmware update with PC companion software
Download PC companion and install
Install PC companion on your PC computer. Follow instruction. For firmware update you need a micro USB cable. When the pc recognizing your XPERIA Ray it will install the necessary driver files.
After your XPERIA Ray connected press Start / in Support Zone
You can also use Sony Ericsson update service tool
PC Suite is out of date use PC companion software instead
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
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.!