Download file from attachment, unpack somewhere to your pc.
Press and hold search button on Play and while keeping it pressed, conect usb cable to PC.
Open folder where you unpacked attachment and double-click on start.bat
Wait few seconds and when windows close, discconect phone and power on. It should be reseted
If you get stuck with "waiting for device" message, you'll need to install drivers
Or you could download Pc Companion from Sony's site and repair it from there