[Darryl Ramm]

Ok but did you run Pro Tools (and App Manager while you are there) uninstall from Control Panel? Did it show both were even installed?

Did you manually download a fresh new Pro Tools installer from Avid.com?

Check your account has administrator privileges.

You can look for Avid or Pro Tools folders (not your plugin folders!) left after running the uninstaller and manually delete them.

Trying to do much more than that, rooting around in the registry etc. and cleaning out keys may or may not be worth the effort. Do you have a recent backup? Otherwise a clean Windows install may be in your future.