It’s one of the “plugins” that is part of stock Rhino, so if it’s not there something is wrong with your Rhino installation. Try reinstalling Rhino…are you running it in safe mode all the time? Something is wrong.
Hello - please update your Rhino to the latest version. You’ll also need to reinstall video drivers, it looks like, and if you can, get more RAM in the machine, 8 GB is pretty small for Windows 10. The main thing is to update Rhino and see how that works,