please help me to correct the following c# code

First, you need to fix the check as Albin advised. This is not enough, because when you focus any other control, the keyboard input with go there and will not reach the Form.

One simple work-around would: in the code, traverse all child controls (using Control.Controls) recursively and add the same key press event handler.

However, the hole idea of using this key press suggests you need to improve your UI style. Why not simply having a button and/or menu item. It least they would be self-describing, but for your key press your will need to document this non-standard key press. Also, you can more successfully use menu hot key. It would not require an unnatural work-around.

—SA

I don't know if you have solved your problem yet but the only method that I know of resolving multiple keypresses reliably is by the use of the Windows API.

Specifically the GetKetstate()[^] function. How to declare it in your program[^].

Use it something like:

bool np1 = (((ushort) GetKeyState(VK_NUMPAD1)) & 0xffff) != 0;
bool np3  = (((ushort) GetKeyState(VK_NUMPAD3)) & 0xffff) != 0;

if (np1 && np3)
{
  // do whatever you want to do if they are both pressed
}

Hope this helps.

[Edit - Added information]
Take a look at When KeyPressed / KeyDown just isn't enough. An adventure in GetKeyboardState.[^] which shows how to use GetKeyState() and also has a small app that you can examine.
[/Edit]

It will not enter your if statement because e.Key only references the most recently pressed key, so it cant be equal to 2 different keys at once.

Try this instead(if i understand you correctly)
Put a label in ti your form and see the outcome..

private List<Keys> pressedKeys = new List<Keys>();  
private void Form1_KeyDown(object sender, KeyEventArgs e) 
{    
   pressedKeys.Add(e.KeyCode);      
   printPressedKeys(); 
}  
private void Form1_KeyUp(object sender, KeyEventArgs e) 
{     
   pressedKeys.Remove(e.KeyCode);      
   printPressedKeys(); 
}  
private void printPressedKeys() 
{     
   label1.Text = string.Empty;     
   foreach (var key in pressedKeys)     
   {         
      label1.Text += key.ToString() + Environment.NewLine;     
   } 
}