In /includes/configure.php there is option i.e.
Code:
 define('DIR_FS_DOWNLOAD', DIR_FS_CATALOG . 'download/');
Set url or folder instead of 'download' as required..
have seen other posts on these forums
regarding similar circumstances to your own..
quick SEARCH may also help
AS ALWAYS, BACKUP EVERTHING FIRST, INCLUDING MYSQL, BEFORE
ALTERING config files