An example user terminal device includes a display unit, including a display, configured to display a lock screen. The lock screen includes content representative information representing content included in a message that is provided by an acquaintance of a user of the user terminal device, and a first user interface element. A control unit, including a processor, is configured to, when a user input signal is received via the first user interface element, execute an application capable of reproducing the content and to reproduce the content.