Solution
Try to restart the service using the executable:
For LabVIEW 2010-2012, the NI Service Locator was integrated into the NI System Web Server. The executable is located at <Program Files>\National Instruments\Shared\NI WebServer\SystemWebServer.exe. If you receive an error that mentions the NI Service Locator, any relevant troubleshooting steps should be performed with the System Web Server.
From LabVIEW 2013 onward, the NI System Web Server and NI Service Locator were split into separate components again. The executable of the NI Service Locator is located at <Program Files>\National Instruments\Shared\nisvcloc.