1. A method for operating a mobile terminal, the method comprising: presenting help information prompting a voice input requesting an execution of a search function for functions of the mobile terminal; displaying a list of function items for the mobile terminal in response to a receipt of the voice input requesting the execution of the search function for the functions of the mobile terminal; displaying detailed information related to a function item when the function item is selected from the list of function items based on a user input; and executing the function item in response to a receipt of a voice command based on at least a part of the detailed information.