HVAC contractor not returning - how to pickup the pieces and continue

Hi Experts:
The HVAC contractor was halfway installing our new heat pump HVAC system and the work was stopped due to covid-19 so he could not complete the installation. Now that we are allowed by the city to continue, my contractor is no where to be found. Apology for not knowing all the technical terms, but the work that was already done include installing the air handling unit and all the duct work. There is also a copper line that goes to the side of the house which I believe where the condenser is supposed to be. No condenser has been installed yet. There is some electrical wire from the air handling unit stapled to a rafter. This is known to me since an electrician is responsible for the electrical connection (not the HVAC contractor). No vent covering or make up air covering have been installed. In their places are hard card board to cover the openings. Please tell me what are missing and what's involved to get this project restarted so we can get it completed. Sorry, I know I may not be detailed enough, but I don't know what else to describe. Thank you.