i cannot download films please help i have tried everything

Well if you have tried "everything" there's nothing we can suggest.

😉

Okay....

iTunes error -45054 - https://discussions.apple.com/thread/5469367?answerId=23478840022#23478840022 - permissions error, try repairing disk permissions using Disk Utility.

Using Disk Utility to verify or repair disks - http://support.apple.com/kb/HT1782 - Ignore false warnings this may produce.

If repairing permissions using Disk Utility does not work, try: iTunes: Missing folder or incorrect permissions may prevent authorization - http://support.apple.com/kb/TS1277

Are you doing exactly as the instructions in the third link say? The instructions do not say anything about a file named iTunes, it talks about a setting permissions on or creating a folder called Shared. There will likely already be a folder in Users with your user name on it but if that is the only one then you need to follow the instructions for creating one called Shared.

Are you using the most current version of iTunes? I've been having this problem and repairing disk permissions didn't fix it. As soon as I updated to the latest version of iTunes I finally stopped getting that error code. Best of luck!