Xperia V touchscreen doesn't respond I ordered this brand new xperia V a few days ago and recieved it today. everything's working fine (the power key, volume buttons) the phone starts up good but the phone doesn't respond to touch inputs.
I've talked to the vendor and they asked me to send it to them for replacement but i really don't want to wait another week (maybe more) to use this device

Can it be a software related problem? If yes, What should i try? sony update or something else?
Since you said the phone is brand new there is nothing wrong with the software. It is most probably a defect with the screen. Get it replaced and use a proper phone.