Audiovox SMT 5600 / SPV C500 (HTC Typhoon)

It seems that my 5600 which is running 2003SE is stuck on the "headset" profile. I cannot change it to another one. This is problematic because without a headset plugged in, I cannot hear the caller and they cannot hear me! What should I do? Is there any way I can reinstall the OS? And if I were to do that, where would I get a copy of it to reinstall? Is there another way to fix it besides reinstalling the OS?
Thanks.