2002 Jeep Wrangler No air flow from dash vents

In 2007 my beloved 25 yr old daughter passed away. I inherited her Jeep. To be nice she was dating this JERK.(Ooops did I say that? ) That called himself installing a new stereo system in her jeep, & now now there is no airflow, hot or cold coming from the front dash vents. It does however flow through the vent in the very top of the dash closest 2 the windshield and when you have the a/c on the whole entire windshield fogs up. Then you have to set temp between hot & cold & turn on defrost. Could this be electrical or something else. Or should I just go slap the stupid jerk? (Oops. There I go again. Sorry)