void CheckBox1_CheckedChanged(object sender,EventArgs e)
{
if(CheckBox1.checked=true)
txtPassword.PasswordChar='0';
else
txtPassword.PasswordChar='#';
}
PasswordChar isthe cha racter used to mask characters entered in a single-line TextBox control. Set the value of this property to 0 (character value) if you do not want the control to mask characters as they are typed.