Your clock has a setting which allows it to enter standby mode. If your screen appears dim and the buttons are unresponsive, your clock is probably in standby mode. To take you clock out of standby mode, press the power button. If this does not correct the problem, please view the Button Replacement Guide.
If you have ensured that your clock is plugged into a working outlet and turned on, check the brightness setting by pressing and holding the SNOOZE/DIMMER button on top of the clock. If the display still does not become visible, the screen could be broken, in which case you may want to refer to the Screen Replacement Guide.
First make sure the clock input is set to the correct source for your preferred device, dock for iPhone 5 or newer and auxiliary for all others. Turn up the volume using the onboard volume controls and those on your device. If there is still no music, your speakers may be broken.