I need to backup my HTC Sensation XL, the phone works but the screen is broken.

[AndroiderPete]

One day my HTC Sensation XL Just shut off when i was sitting and righting a messege. I turned it on and it vibrated and played its little melody but the screen was black. I have talked to the place were i bought the phone, and they will give me a new one today. But i need to backup my phone and i dont know how to. Normally there pops up a thing on the phone were you choose if you only want to recharge or if you want to use it as a hardisk. But i cant choose anything... Please help me backup my phone. Thanks.