Have you installed a new version of Alteryx recently? Can you confirm that you are running an admin version of Alteryx. You must have an admin version in order to see the Service.
Another possibility is that for some reason your service was uninstalled for some reason. You can install the service using the command line cd Program Files\Alteryx\bin\alteryxservices.exe \? and use the install function posted.
You also have the option of reinstalling alteryx as well.
If these issues are not resolved by attempting one of these troubleshooting steps, please reach out to our Support team.