A server comprising: a communication unit configured to communicate with a plurality of devices including a display apparatus; a storage unit configured to store a plurality of manuals; and at least one processor configured to: receive, from the display apparatus through the communication unit, a spoken voice signal corresponding to a spoken voice of a user recognised by the display apparatus, and characteristic information of the display apparatus, generate a response signal to the spoken voice signal based on a manual corresponding to the characteristic information of the display apparatus among the plurality of manuals stored in the storage unit, and transmit the response signal to the display apparatus, characterized in that the at least one processor is further configured to: when the spoken voice signal is a signal for an operational state of the display apparatus, diagnose the display apparatus based on the manual and transmit a result of the diagnosis to the display apparatus, and when the operational state of the display apparatus is diagnosed as an error state which can be autonomously solved, transmit a guide message for guiding a solving method for the error state to the display apparatus. a communication unit configured to communicate with a plurality of devices including a display apparatus; a storage unit configured to store a plurality of manuals; and at least one processor configured to: receive, from the display apparatus through the communication unit, a spoken voice signal corresponding to a spoken voice of a user recognised by the display apparatus, and characteristic information of the display apparatus, generate a response signal to the spoken voice signal based on a manual corresponding to the characteristic information of the display apparatus among the plurality of manuals stored in the storage unit, and transmit the response signal to the display apparatus, characterized in that the at least one processor is further configured to: when the spoken voice signal is a signal for an operational state of the display apparatus, diagnose the display apparatus based on the manual and transmit a result of the diagnosis to the display apparatus, and when the operational state of the display apparatus is diagnosed as an error state which can be autonomously solved, transmit a guide message for guiding a solving method for the error state to the display apparatus. receive, from the display apparatus through the communication unit, a spoken voice signal corresponding to a spoken voice of a user recognised by the display apparatus, and characteristic information of the display apparatus, generate a response signal to the spoken voice signal based on a manual corresponding to the characteristic information of the display apparatus among the plurality of manuals stored in the storage unit, and transmit the response signal to the display apparatus, characterized in that the at least one processor is further configured to: when the spoken voice signal is a signal for an operational state of the display apparatus, diagnose the display apparatus based on the manual and transmit a result of the diagnosis to the display apparatus, and when the operational state of the display apparatus is diagnosed as an error state which can be autonomously solved, transmit a guide message for guiding a solving method for the error state to the display apparatus. when the spoken voice signal is a signal for an operational state of the display apparatus, diagnose the display apparatus based on the manual and transmit a result of the diagnosis to the display apparatus, and when the operational state of the display apparatus is diagnosed as an error state which can be autonomously solved, transmit a guide message for guiding a solving method for the error state to the display apparatus.