Hi nauna,
Please refer below sample.
HTML
<asp:RadioButtonList ID="rblYesNo" runat="server">
<asp:ListItem Text="Yes" Value="Yes"></asp:ListItem>
<asp:ListItem Text="No" Value="No"></asp:ListItem>
</asp:RadioButtonList>
<asp:TextBox ID="txtData" runat="server" />
</div>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script type="text/javascript" language="javascript">
$("document").ready(function () {
$("#<%= rblYesNo.ClientID%> input").change(function () {
if ($(this).val() == 'No') {
$('#<%= txtData.ClientID%>').hide();
}
else {
$('#<%= txtData.ClientID%>').show();
document.getElementById('<%=txtData.ClientID%>').value = "I am selected";
}
return false;
});
});
</script>
