The memory button on my TI-84 Plus will not function

There is no such button. The factorial function is in the probability submenu of the math menu. Press MATH left-arrow 4 to access the factorial.

Unfortunately, you can only access RESET from within the menus of the calculator. You will have to remove all of the batteries and let the system naturally reset. The TI-84 Plus uses five batteries: four AAA alkaline batteries and one SR44SW or 303 silver oxide backup battery. The silver oxide battery provides auxiliary power to retain memory while you replace the AAA batteries. Re-install the batteries and reprogram your functions.

Use the memory manager. Press 2ND [MEM] to bring up the memory manager, then 2 7 to bring up the list of programs in memory. Use the arrow keys to move to the one you want to delete, press DEL, then answer Yes to the prompt. Press 2ND [QUIT] to exit the memory manager.

Some variable in your function is in archive memory. Press 2ND [MEM] 2 to get into the Memory Management menu. Press 1 to select All. Do you see a variable you're using in your function with an asterisk to its left? If so, navigate down to it and press ENTER to turn off the asterisk. Do this for as many variables as necessary, then press 2ND [QUIT] to exit.

Try the Solver again.

From the TI knowledge base and FAQ

How do I correct ERR: MEMORY on a TI-83 family or TI-84 Plus family graphing calculator?

An ERR: MEMORY is given when there is not enough memory to perform the instruction or function. To increase available memory by deleting the contents of any variable (real or complex number, list, matrix, Y= variable, program, Apps, AppVars, picture, graph database, or string), follow these steps. • Press [2nd] [MEM] to display the MEMORY menu.
• Press 2: Mem Mgmt/Del.
• Select a variable or data that needs to be deleted and press [ENTER].
• Use the arrow keys to move the cursor next to the item, and then press [DEL]. The variable or data should now be deleted from the memory.
When deleting programs or Apps, a message asking for confirmation will appear. Select 2:Yes to continue. To leave any variable screen without deleting anything, press [2nd] [MODE].
Notes:
With the exemption of programs and Apps, no warning will be given to verify the deletion.Some system variables, such as the last-answer variable Ans and the statistical variable RegEQ, cannot be deleted.

Hope it helps.

Hello,
Reinstalling the calculator OS (not Mirage OS) will wipe out the password.
Hope it helps.

Look at the manual all what you need:
http://education.ti.com/guidebooks/graphing/84p/TI84PlusGuidebook_Part2_EN.pdf
Rate me if it's helped.

Press the 2nd button, then the plus button, the 7, then 1, then 2. This will reset your calculator.

Hello,

if you are out of memory try deleting some applications (or backing them up on your computer).

If you cannot see your (function? ) plots check the window dimensions.

Hope it helps.

Please help me to find the answer for my problem with TI-84:
If I'd like to work with: nDeriv(3X^3+2x^.5),X,1)
then I press Enter button, the sreen shows Error...

Please help me to get the answer for this problem. Thank you very much!