I recently came across this problem and thought it would be an easy fix if I just reinstalled or repaired the itunes application, but I was wrong. If you ever come across the message “Itunes cannot run because some of its required files are missing” here is what you need to do.
1) Uninstall itunes and quicktime player. (don’t worry your music and videos will be fine as they are stored in a different folder than the itunes program and you will not lose your music.)
2) Uninstall quicktime player. Then restart your comptuer.
3) Now go to www.itunes.com and download the latest version of itunes and install this. It will install itunes and quicktime player. Once this is installed you will now be able to open up the itunes application and everything should be back to normal working condition.
I’m not sure why this error message comes up and wasn’t able to find out how or what causes this but doing a repair or reinstall will not fix this problem. Anyways, I hope this helps some of you and some of the fustration on this odd error.