Replace the TI-84 Plus' internal batteries. A low or nonexistent battery charge can cause the calculator to be slow or completely unresponsive. Turn the calculator over and push down on the battery cover's latch to pop it open. Remove all of the AAA batteries and replace with new ones. Make sure the polarity of the batteries matches the "+" and "-" signs inside the battery compartment. If the TI-84 calculator still does not respond, you may need to replace the silver oxide battery. This battery is found inside the main battery compartment adjacent to the AAA battery slots. This battery only needs to be replaced every three years.

Review any error messages displayed on the screen if you are experiencing errors when entering calculations. Typically, the error message clearly tells you what to do to fix the equation. In most cases, the messages will provide the option to select "Goto" or "Quit." Always select "Goto" to have the TI-84 direct you to the exact problem in the problem equation.

Hold the "Window" button to adjust the zoom of the screen if you cannot make out the details on your graphs. Zoom problems occasionally happen when you zoom too far, or manually set customized window boundaries.

Press "Window" and increase your "Xscl" and "Yscl" values using the keypad if the screen appears completely dark. A dark screen is usually a software issue rather than a hardware issue, and occurs when you set the values for the graph lines so small that they merge together into an even black shape.

Adjust the contrast if you are experiencing readability issues with the screen's text color. Press and release the "2nd" button, which is found at the top of the keypad and colored yellow. A blinking arrow will appear on the TI-84 Plus' screen. Press the blue-colored "Up" or "Down" arrows to lighten or darken the screen contrast. Stop when you have achieved a level of easy readability.