Personally, I haven't seen the search box in years. But it is called the address bar, not task bar. There is also a setting to show/hide the speed dial search box, and the instant search - so make sure you have the right one. The one for the address bar is under Settings > Advanced > Address bar. (The actual task bar - the bottom line on you screen - is part of Windows and not under Opera's control. If you have a search box in the actual task bar you'll need to change that in Windows settings, not in Opera settings.)
