If you have the old hard drive and can still read its contents, look for a folder on it named SWSetup, your webcam software installer will be in one of those folders, they are not always clearly labeled, look in each folder for clues at what the software is. Mine is located in the Youcam folder.
If you do not have access to the old drive, the only recourse to get the original Free software back is to use your HP Recovery Media to reinstall the OS and all original software.
Yes you can install YouCam Standard for a small fee