You've got one of two options.
You can either DIY, or take it to a local repair shop.
The price itself isn't very expensive, but it's a bit difficult to replace if you've never done it before.
But here's the replacement part:
http://www.ebay.com/itm/HTC-Sensation-4G-Flex-Cable-Ribbon-Camera-Socket-Headphone-Jack-Power-Button-/221060200627?pt=US_Cell_Phone_Replacement_Parts_Tools&hash=item337836f8b3
I wish you luck.