I found this maybe it will help. "
As a last result, try to reinstall the OS. To do this follow the steps below:
1) (TI-84 Plus CE only ) While holding the [2nd] [Del] keys down, press and release the RESET button on the back of the calculator. The message "Waiting... Please Install Calculator Software" should appear. At this point, it will be necessary to reinstall the calculator's operating system.
2) Connect the calculator to the computer and verify the USB cable is completely pushed into the TI-84 Plus CE using a standard A to mini B USB Cable and it is a tight fit. If it is not completely pushed in the computer will not detect it.
3) Open the TI Connect™ CE Software
4) Turn the calculator on. Make sure the calculator appears in the TI Connect CE™ Software Content Panel in the TI Connect CE ™ Software, click on “Actions” and then “Send OS.” (Warning: Do not disconnect the cable during a transfer.)
5) Navigate to the OS file you saved on your computer.
6) Click “Open".
Alternatively, you may drag and drop the OS file you saved on your computer from your computer to your calculator in the “Calculator Explorer” workspace.
Please Note: If the above steps do not work and you are using a TI-84 Plus CE please try the steps in Kbase#37116 if your calculator is unresponsive."