The first thing you have to do is re-install an antivirus to clean the infected files. Most likely, the EXE was infected too and deleted by the antivirus. You can find a list with antivirus applications using the following link. Secondly, to avoid losing your data, install the Password Protection Manager on another computer using installer from the download page and copy only the EXE file. Transfer it using a USB drive and place the file in its original location then launch the software.