In the upper right corner of the control panel (just below your name) is the item search box.

To search for an item, simply enter some text that you expect to be in the item title or in the cover sheet content and press the enter key.

The results of your search will be displayed. 

You can further limit your search by choosing which board's items to search, whether the item is parked, is in a meeting in development, or is in a finalized meeting. You can also specify a date range to search

The listed items indicate if the item is parked or in a meeting. If the item is in a meeting that is in development or is parked, and you have access privileges to view the item, there will be a View Item icon displayed.