When you encounter the error message stating that the local print Spooler service is not running while trying to add your Samsung SCX 4x21F mono laser printer, you will need to follow these steps to resolve the issue: 
Steps to Restart the Print Spooler Service:
 
- Open Windows Services:
- Press Win + R on your keyboard to open the Run dialog.
- Type services.msc and press Enter to open the Services window.
 []Locate Print Spooler:
- Scroll down in the Services window to find Print Spooler.
 []Restart Print Spooler:
- Right-click on Print Spooler and select Restart from the context menu.
 []Set...