If all you're doing is clearing the text boxes on your web page, you don't really want to do a post back, do it in JavaScript instead.
E.g. (Javascript)
Go to the HTML editor in Visual Studio (if you are using that, it's a tab at the bottom of the design screen), otherwise, edit the .ASPX file
put this code inside the <head> element
CODE
<script language="javascript" type="text/javascript">
function clearinputs(sType) {
a = document.getElementsByTagName("input");
for(i = 0; i < a.length; i++) {
if(a[i].type==sType) {
a[i].value = "";
}
}
}
</script>
and somewhere else (where you want the button), but this code
CODE
<button onclick="clearinputs('text');">Reset</button>
And then you won't need a post-back (wasting precious client/server time)
I know this isn't C#, but if you're doing web programming, you better learn HTML and JavaScript.