How to fix the broken power button of my Desire HD?

Hi, I was out the other day and dropped my phone, top hit the ground first. I picked up the phone and was relieved that it was working fine, so I continued to use it. But then the battery ran out and phone went dead. I plugged in the charger, fully charged it and then tried to switch the phone on again. Nothing happened. This is when I first realized that power button is broken, it would not click.

I tried searching for a solution but nothing seems to work. Tried fiddling with and pushing out the power button; tried removing the battery and inserting it back in while plugged to a wall socket and laptop. I cannot give the phone for repairs with personal data on it. Please help me switch my phone on again.