It is just not working. it is freezing on me?

When you change the batteries the display reverts to default setting. My optimistic guess is that the screen display is so light that you cannot see anything on it. This can be arranged.

A Try this before thinking of repairs.

1. Push the ON button.
   
2. Even if you see nothing, press the [2nd] key and release it.
3. Press and HOLD the UpArrow key until the screen darkens.
4. You may have to keep pressing UpArrow for a little while before you see anything.

1. Remove one of the AAA batteries.
   
2. Press and hold the [CLEAR] key.
   
3. Whileholding [CLEAR], reinsert the AAA battery and then
   
4. turn the calculatoron.
   
5. The calculator should display the message "RAM Cleared".
   
6. Release the [CLEAR] key and then press it one more time to remove the message "RAM Cleared".

1. Remove batteries including the backup battery for 5minutes.
   
2. After the 5 minute period, reinsert all of the batteries and
   
3. turn the calculator on.
   
4. Adjust the contrast if necessary.

1. Remove one of the AAA batteries.
   
2. Press and hold the [DEL] key.
   
3. Whileholding [DEL], reinsert the AAA battery and then
   
4. turn the calculatoron.
   
5. The calculator should display "Waiting...Please install calculator software now".
6. Connect the TI Connectivity cable between the computer and the calculator.
7. Click on Start >> Programs >> TI Tools >> TI Connect >> TI OSDownloader.
8. Follow the on-screen directions to reinstall the calculator's OS.