How do I restore the sound to my Lightware VP100?

I purchased a used Lightware VP100 (http://www.projectorcentral.com/Lightware-VP100.htm) and it was fully operational. I then connected two mini external speakers and a portable DVD player to the projector and no video or audio functioned. When I reconnected the original DVD player the video was fine, but I had no sound. I have exhausted every venue I know of to no avail. What has happened, blown speakers?