2002 Subaru WRX Stereo Issues?

My wife has a 2002 Subaru WRX with a stock 6-disc changer. Over the weekend, she put a disc in and tried to switch the changer to the proper disc, and the stereo shut down. now we can get the tape player and radio to work, but the CD function is completely unresponsive. Has anyone ever experienced/resolved this? If not, does anyone have any advice for how to either completely reset the stereo so it will spit out the discs currently in there, if possible?