Hi Ramachandra,
if you want to access the control of one content page, you could not use the id that you set in the properities dialog, you shoud run your page and look up the id in the view source,
for example, In one content page, I set a TextBox's id is TextBox1, if I want to access it use javascript language like this: document.getelementbyID(''ctl00_ContentPlaceHolder1_TextBox1);