My subwoofer randomly stopped working...

[Joseph Tortorello]

About 2 months ago, I purchased come Cyber Acoustics speakers, which are pretty compact and come with an 8w subwoofer. The other day, I unplugged the subwoofer to indicate to my friend how it would sound without. When I plugged the subwoofer back in, it did not work. The subwoofer plugs in with a 3.5mm jack, so I plugged it directly into my PC, and it did function, however, it still won't when plugged into the indicated spot on the speaker system. There are no fuses in the system. Any suggestions on how to get it to work again?

 

Here are images of both sides of the board. The black plug is the 9v DC input and the gray is the subwoofer output.