[C#.NET CODE STARTS]
 
// namespace declaration
using System.Management;
 
// code sample for setting default printer
 
ManagementObjectCollection objManagementColl;
// class used to invoke the query for specified management collection
ManagementObjectSearcher objManagementSearch = new ManagementObjectSearcher("SELECT * FROM Win32_Printer");
 
// invokes the specified query and returns the resulting collection
objManagementColl = objManagementSearch.Get();
 
foreach(ManagementObject objManage in objManagementColl)
    {
       if (objManage["Name"].ToString() == "RequiredPrinterName")  // compares the name of printers
          {
             objManage.InvokeMethod("SetDefaultPrinter", null); // invoke [SetDefaultPrinter] method 
             break;
           }
      }
 
[C#.NET CODE END]