How to lock workstation programmatically? (C#)

There is no such .NET function (or at least I didn’t find). Fortunately we can use PInvoke instead.
Use this function to lock workstation’s display to protect from unauthorized use. Result of this function is the same as pressing Ctrl+Alt+Del.

1. Add namespace at the top of your code:
   

   	using System.Runtime.InteropServices;
   	

2. Declare PInvoke:
   

   	[DllImport("user32.dll", SetLastError = true)]
   	

   	static extern bool LockWorkStation();
   	

3. Call this function like this:
   

   	if (!LockWorkStation())
   	

   	   throw new Win32Exception(Marshal.GetLastWin32Error());