I don't see a setting to disable or reassign the camera button on the side of the device. This is likely a hardware issue with the phone that will need to be taken in for repair. I can find you the nearest repair location and create an appointment if you like. Do you have phone insurance? I would be happy to check for you if you don't know.
Also Lindsay, the side Camera key is labeled a "shortcut" from the userguide. On pg.92, it states that the camera CAN be activated from the main menu and that the "capture" function is assigned to the left soft key while the camera is active. duhhhhhhhhh ~ are you not able to take a picture this way as well?