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Hi.. Friends, I want to make a such type of application in which I can lock my computer using user name and password, in my c# window application, if user enter the correct username and password then computer will be unlock. I have no no idea about this, would you please help me?

Thanks & Regards in advance
Parveen Rathi

First method, probably the simplest:

System.Diagnostics.Process.Start("Rundll32.exe", "User32dll,LockWorkStation");


Nearly the same, without running a child process, immediately from the calling process:

class LockIt {
   internal static extern void LockWorkStation();

That's is.

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Parveen Rathi 29-Feb-12 1:10am    
But how i unlock it again?
Here is the sample windows application which does this task by using two APIs from user32.dll.

namespace Lock_Display
    static class Program
        private const int WmSyscommand = 0x0112;
        private const int ScMonitorpower = 0xF170;
        private const int HwndBroadcast = 0xFFFF;
        private const int ShutOffDisplay = 2;
        private static extern void LockWorkStation();
        [DllImport("user32.dll", SetLastError = true)]
        private static extern bool PostMessage(IntPtr hWnd, uint msg,
                      IntPtr wParam, IntPtr lParam);
        private static void TurnOffDisplay()
            PostMessage((IntPtr)HwndBroadcast, (uint)WmSyscommand,
                    (IntPtr)ScMonitorpower, (IntPtr)ShutOffDisplay);
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        static void Main()
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Sergey Alexandrovich Kryukov 29-Feb-12 0:43am    
I do not understand why it's so complex. My two solutions work, my simpler. Want to see?
Parveen Rathi 29-Feb-12 1:04am    
Yes. my pleasure
Parveen Rathi 29-Feb-12 1:07am    
with this code I lock my computer and how can i unlock it again? and where I place your code?

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