Audio for laptop only affected when logged on

I recently encountered a problem with my laptop, a dell latitude d620, this problem being my eight year old little brother. He was listening to music on my laptop with headphones in the port, dropped it on the sound port side, jamming my audio system entirely. However, this problem is only registered when an account is logged on to my computer. My laptop only registers mute or headsets when an account is logged on, not at the log in screen, how do I manually remove the assumed acknowledgement of non-existent headphones from my computer without having to take it apart?