Instructions
Turn on the TI-89 calculator and press the "2nd" and "6" buttons simultaneously. This key combination gives you access to the calculator's memory menu.
Press "F1" to get to the Reset menu. Press the "Right Arrow" key once to access the "RAM" menu and then the "Down Arrow" key once to highlight "Default."
Press the "Enter" to reset the calculator to the factory settings. Press the "Enter" key again when asked to confirm your settings.