I have a Iphone 5s and the screen nor the touch button does not work, how would I unlock my phone to back it up on iTunes?

HI all, I think the Primary/Secondary IC touch control sensor has messed up and my screens not working. I had a faulty home button in which the sensor doesn't work. As I was going to get my phone repaired, I wanted to back it up on iTunes and it requires that the phone has to be unlocked so How would I be able to unlock my phone without the screen working? Would appreciate if anybody has a solutions! Thanks in advance x