Can someone please help me with a listbox whcih has 2 values on each listitem. for Example AAA, 111
                      BBB, 222

How to retrieve the value and store them in text box

Please help.

mmm, have I understood you correctly?

1..You have a select box, EG:
   <option>AAA,111</option>
2..If AAA,111 is selected you want to place them in a textarea?
   <textarea>AAA,111</option>

If so this would be better suited in the JavaScript forum, anyway:
<script>
function moveValues()
{
  if (document.fromName.selectBoxName.value == "AAA,111")
  {
    document.fromName.textAreaName.value = "AAA,111"
  }
  else if (document.fromName.seectBoxName.value == "someOtherValue")
  {
     document.fromName.textAreaName.value = "someOtherValue"
  }
}
</script>

Then in your select tag fire the function onChange:
<select name="selectBoxName" onChange="moveText();">

Wind is your friend
Matt