When I click on a help link or button in Prism, no help screens come up.

Prism since version 6 uses web-based help. When you click on a help link (or button or menu item), Prism asks Windows or MacOS to open a certain URL in the default browser. If no help page opens, somehow Windows or MacOS is not sure what to do when told to open a .file with the .htm extension. Use the Windows or Mac control panel to link .htm files to your favorite web browser. The details depend on which version of Windows or MacOS you use.