Uninstall and re-install PT would be one option. If that fails, rebuilding your system drive from scratch is a better option(and yes, I feel your pain
). Your BEST option, unfortunately may not be available and that would be to recover from a drive image, done when things were running great. Since there are 2 kinds of computer users; those that Have had a catastrophe, and those that WILL have a catastrophe, Research "drive imaging" and cover your aSSets before the next disaster. I never even install an update or a new plugin without having a backup plan. I keep a pair of 2TB USB drives that do nothing but hold drive images of all my computers, and images of my Pro Tools machine in several stages(PT10.3.5, 10.3.8, 11.1, 11.3.1) and I also have a cloned spare system drive, so if I have a total crash or a virus attack, I remove and replace the system drive and go back to work.
1 last tip, quite often in the case of a virus attack, removing the system drive, placing in a drive case or dock(USB) and connecting to another computer will allow you to remove a stubborn virus(this has worked for me on 2 occasions already on my home machine). As for my audio machine, about every 6 months, I download the latest versions of Spybot and MalwareBytes, run them until they report all clean, then uninstall them.
BTW, since some tech was in your machine, I would review all the required system tweaks as many things might have been changed "under the hood"
