The volume down button on my iPhone 5 hasn't worked for a long time, but I finally got around to trying to fix it tonight. Bending seemed unlikely to me, as I've always carried it in my front pocket, protected by a case. A lot of switches stop working due to the switch contacts oxidizing, so I decided to attack it from that direction. I didn't have any electronic contact cleaner handy, but I did have some 91% Isopropyl Alcohol, so I soaked a cotton ball and began dripping some alcohol onto both the up and down volume buttons, then working the buttons, and repeating for several minutes until the down volume button began working again. Hope this helps someone.