C# how to get text value from PasswordBox?

You can get it from the Password property.

You may extract it from Password property:

passwordBox.Password.ToString()

If using a MaskedTextbox you can use the .text property. For example:

private void btnOk_Click(object sender, EventArgs e)
{
    if ( myMaskedTextbox.Text.Equals(PASSWORD) )
    {
        //do something
    }         

}