Why would there suddenly be no sound and no radio reception?

When I plugged in my headphones recently, I could not hear any music through them, and when I tried to access the radio, I got the message "No Radio Signal. Please plug in headphones for radio reception". I tested my headphones on my 5th generation iPod and other devices and they work normally. The battery is fully charged and the iPod seems to be working otherwise.

What is a possible cause of this, and is there any way to fix this myself?