<p>As the title suggests, I am having trouble maintaining my code on postback. I have a bunch of jQuery code in the Head section and this works fine until a postback occurs after which it ceases to function! </p>

<p>How can I fix this? Does the head not get read on postback, and is there a way in which I can force this to happen? </p>

<p>JavaScript is:</p>

<pre class="lang-html prettyprint-override"><code>        &lt;script type="text/javascript"&gt;
        $(document).ready(function()
        {
            $('.tablesorter tbody tr').tablesorter();

        $('.tablesearch tbody tr').quicksearch({
            position: 'before',
            attached: 'table.tablesearch',
            stripeRowClass: ['odd', 'even'],
            labelText: 'Search:',
            delay: 100
        });
       }); 
        &lt;/script&gt;
</code></pre>

If you just have that code hard coded into your page's head then a post back won't affect it. I would check the following by debugging (FireBug in FireFox is a good debugger):
Verify the script is still in the head on postback.
verify that the css classes are in fact attached to some element in the page.
verify that the jquery code is executing after the browser is done loading on post back.
EDIT: Are you using UpdatePanels for your post back? In other words is this an asynchronous postback or a normal full page refresh?
EDIT EDIT:  AHhhhh... Ok. So if you're using UpdatePanels then the document's ready state is already in the ready so that portion of jquery code won't be fired again. I would extract the jquery delegate out to a separate function that you can also call after the async postback.