Day 1 Newbie Very Frustrated

I’ll leave Ulf to weigh in on the issues relating to the audio devices on your computer, but I just wanted to chime in to say that I doubt that uninstalling and reinstalling Dorico would really have any bearing on this. You could try running the clean-up script, which is linked to from the FAQ thread, which will reset Dorico back to its factory settings, and perhaps might get you back up and running.