each of the options has a selected property which you can set to false, 
like this:
function deSelect(objSelect) {
	for (var i=0; i<objSelect.length; i++)	
		objSelect.options[i].selected = false;
}

you would use something like deSelect(document.formname.selectname) to 
call this function.

HTH
Phil
> Is there way to Unselect the options within the the combo box after the 
> alert  messagage. ( so that none of teh option is selected?)
> 
> let me know, if anyone knows the solution.
> Thanks,
> 
> Sukhi