You could have a bad device connection. In order to fix this, you need to make sure the device is charged/plugged in. Remove your phone/iPhone and wait 10 seconds before placing it in again. Also make sure that the volume is actually turned up on the device. Make sure your phone/iPod is playing music and that the volume is turned up on your device. Also try restarting your phone/iPod or unplugging and replugging in the sound system, seeing as that could be the problem. These simple fixes could solve your problem. If that doesn't work, go to the the troubleshooting page found at Bose SoundDock Portable v2 Troubleshooting or visit the replacement guide at Bose SoundDock Portable v2 Speaker Replacement if the speaker is your diagnosed problem.
The SoundDock needs to be plugging in or charged in order for the device to charge your phone/iPod. If that isn't the problem then your phone case or dust/debris could be blocking the connection. Something may also be blocking your connection, so remove any protective case that might impede the connection of your iPod/iPhone to the dock. There may be dust/dirt stopping the port on your device from connecting properly. You could try blowing gently on the 30 pin connection on the dock to remove any dust then do the same in your iPhone/iPod. If none of that works out, then you might need a full dock replacement which can be found at Bose SoundDock Portable v2 Docking System Board Replacement for the replacement after troubleshooting has been done which you can find at Bose SoundDock Portable v2 Troubleshooting