I have a 2009 iMac and I am having some issues with iMovie. I already tried a fix: trash preference folder,com.apple. apps.plist without success. Can I somehow reinstall iMovie 11 and hopefully get rid of all issues with iTunes and iPhoto?

The problem is when importing itunes (or Iphot) files into Imovie projects. It tells me to open Itunes so it can show all files (songs) . Itune opens up but there no files showing. Itunes or iphot work fine stand alone. I went into libray-preference menu, trying to find and trash com.apple.imovieapp.plist, and com.apple.iapps.plit and coudn't find such files. They dont exist here. So can I somehow reinstall Imovie 11 and hopefully get rid off all Imovie issues this way? Do I need get Imovie 11 from apple store and pay for it again?