I wonder if the problem is with running your sql string through sprintf.
sprintf is going to attempt to process the % signs first, and the net result is that your % signs will be disappearing from the sql query.
Check out the sprintf docs:
PHP: sprintf - Manual
I do the exact same thing you do in my system, however I dont use sprintf.
Try this instead:
$query = "SELECT title, subtitle, button, price, ItemNo, instock, search1, search2 FROM inventory WHERE title LIKE '%naruto%' ORDER BY title ASC";
If you HAVE to use sprintf for some other reason, then try escaping the % symbols.
I hope that helps!