At times the public PCs may exhibit a "no audio output device" error preventing users from using headphones. 

This issue is caused by the USB hub found top side near the keyboard & monitor.  This device will at times act up and cause the aforementioned error. 

To resolve, simply remove the USB cable from the rear (circled in red below) and plug back in, then audio will work. This will allow Windows to redetect the device and work normally.