If you want to check that you have the latest iTunes version, follow this.
1. Step Open iTunes
2. Step Click on Help and then on Check for Updates
3. Step Follow the instructions on the screen to check for the newest iTunes version and then download it:
4. Step An iTunes update can be as large as 60 – 100MB:
If you want to downgrade you need to uninstall iTunes first.
If you still have trouble checking for iTunes updates because you are using an older version of iTunes post your problems here. You can also always download the latest iTunes at apple.com