Share your experience!
Hi guys. I have this problem with my keyboard. I hardly type "P" button. Whenever i type "p" it always shows "o". My fingers isn't wet and i already tried rubbing my phone's screen. Can you help with this? 
Repair your phone
Update Service (SUS)
http://www.sonymobile.com/gb/tools/update-service/
http://www-support-downloads.sonymobile.com/Software%20Downloads/Update_Service_Setup-2.11.12.5.exe
Bridge (for Mac)
Alternatives on How to backup Xperias
http://talk.sonymobile.com/thread/36355
Don't forget to give Kudos (Click on the half star + )
You can also test your phone
https://play.google.com/store/apps/details?id=com.sonymobile.androidapp.functiontester
note:take full backup of data
try *#*#service#*#* on the dialer go to test services check if it doesn't then get your phone replaced if in warranty
i had same issue, went to sony service center showed it ..............they assured me for replacement....., but when i got replacement the NEW Xperia GO it had headphone jack problem so again in for replacement..............still awaiting replacement..........tale of yesterday...........happyness spoiled but not lost: courtesy SONY Service
hope this helps