If u want to clear all the text box and change other controls to inital mode then u can simply have your controls inside a form and then use the following code
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<script language="javascript">
fromreset()
{
myform.reset(); //will reset all the controls in ur page to initial stage.
(or)
document.myform.[textbox Id] = " "; // will clear the textbox alone
}
<form name="myform" id="myform">
your code
may be you have some button ... on that button's onclick option