JSI Tip 8964. How do I resolve Common 'Windows Installer' Problems?

MVP Yuval Sinay authored the following COMMUNITY SOLUTIONS article 555175, which begins with:

When you try to install/uninstall some application/s, you may get warning messages like:

"The Windows Installer Service could not be accessed"

"Windows Installer Service couldn’t be started"

"Could not start the Windows Installer service on Local Computer. Error 5: Access is denied."