Check out example codes for "c# keyboard enter". It will help you in understanding the concepts better.

Code Example 1

You must try this in keydown event

here is the code for that :

private void textBox1_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Enter)
        {
            MessageBox.Show("Enter pressed");
        }
    }
Update :

Also you can do this with keypress event.

Try This :

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (e.KeyChar == Convert.ToChar(Keys.Return))
        {
            MessageBox.Show("Key pressed");
        }
    }

Code Example 2

private void textBox1_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Enter)
        {
            MessageBox.Show("Enter pressed");
        }
    }

Learn ReactJs, React Native from akashmittal.com