Download Xperia Companion, plug your phone to the computer and click "Repair my phone" or something like this :) It will factory reset your phone. Sorry for my english.
Sony software update.apk
I don't know, what's this, so I don't included it in package below.
You know what to do with this :D (I can't post links yet :()
Oh, sorry for my english.
Też się mogę pochwalić swoim językiem ;)...