ทำให้ TextBox ReadOnly=True หากติ๊ก RadioButton 1 และเมื่อ ติ๊ก RadioButton 2 ให้TextBox = false เหมือนเดิม

html, body, form
{
    margin: 0;
    padding: 0;
}

.aspNetDisabled /* Auto generate by ASP.NET */
{
    color: Beer;
    border: 2px transparent;
}

html, body, form
{
    margin: 0;
    padding: 0;
}

.aspNetDisabled input[type="text"] /* Auto generate by ASP.NET */
{
    color: Beer;
    border: 2px transparent;
}

html, body, form
{
    margin: 0;
    padding: 0;
}

input[type=text].aspNetDisabled  /* Auto generate by ASP.NET */
{
    color: yellow;
    border: 2px transparent;
}

input[type="text"].aspNetDisabled  /* Auto generate by ASP.NET */
{
    color: yellow;
    border: 2px transparent;
}

input[name=txtChonic].aspNetDisabled  /* Auto generate by ASP.NET */
{
    color: red;
    border: 2px transparent;
}