My Xperia U screen is blank

[Reacher43]

Right so basically i havent dropped my phone or got water on it or anything, i was using it the other day, put it down for an hour came back to it and the screen was completely blank. 

The whole phone still works, the volume, the touch screen still works everything. Just it is blank, like all the LCD display has died. 

I dont know what to do, someone please help!

P.S.

I have already tried taking out the battery multiple times and waiting, and have also tried to hold the power and volume up buttons to reboot the phone. Nothing works!

[Hampus]

Hi and welcome to the community! Since you're new please be sure that you have checked out our Discussion guidelines.

I suggest that you perform a software repair to exclude software related problems. You can do this via our program PC Companion:
http://support.sonymobile.com/global-en/tools/pc-companion/

In PC Companion you press start on Support Zone > Start on Update the phone/tablet software > Repair phone/tablet (the blue clickable link in the message) > Follow these steps without having your device connected to the PC.

Follow the instruction that appears in the program and do not connect your device until this guide tells you how to connect it.