how to make unsortable header colmn in theme_table drupal 6
Looking at the code for tablesort_header the sortable stuff is only added if the particular header item is an array. So you can cancel off certain columns by just setting the header to a string, e.g.:

$tableHeader = array(
  'This colum header is not sortable.',
  array('data' =&gt; 'Article','field' =&gt; 'a.title'),
  array('data' =&gt; 'From date','field' =&gt; ''),
  array('data' =&gt; 'To date','field' =&gt; ''),
  array('data' =&gt; 'Perpetual','field' =&gt; ''),
  array('data' =&gt; 'Access type ','field' =&gt; ''),
);