try use this code:
<script language="javascript" type="text/javascript">
function Radio1_onclick() {
document.getElementById('<%= TextBox1.ClientID %>').disabled = false;
}
function Radio2_onclick() {
document.getElementById('<%= TextBox2.ClientID %>').disabled = false;
}
function Radio3_onclick() {
document.getElementById('<%= TextBox1.ClientID %>').disabled = false;
document.getElementById('<%= TextBox2.ClientID %>').disabled = false;
}
</script>
or this code:
<script language="javascript" type="text/javascript">
function Radio_onclick() {
if(document.getElementById('Radio1').checked){
document.getElementById('<%= TextBox1.ClientID %>').disabled = false;
}
else if(document.getElementById('Radio2').checked){
document.getElementById('<%= TextBox2.ClientID %>').disabled = false;
}
else if(document.getElementById('Radio3').checked){
document.getElementById('<%= TextBox1.ClientID %>').disabled = false;
document.getElementById('<%= TextBox2.ClientID %>').disabled = false;
}
</script>
call Radio_onclick function all radio button onclick event.