Resolution
Parallels Plesk Panel can be uninstalled using the Add/Remove Programs wizard or by running the Plesk installer program and selecting the Uninstall option.The folders %plesk_dir% (usually C:\Program Files\SWsoft\Plesk) and %plesk_vhosts% (usually C:\Inetpub\vhosts) should be manually removed.
Once done, Parallels Plesk Panel can be installed again.
WARNING: This article provides the steps for complete Parallels Plesk Panel reinstallation. ALL DATA will be lost in this case. Do a full Plesk backup before you reinstall Plesk if you need to save any Plesk data.