modified storage settings and lost files??

My daughter's videos have filled up my computer, so I tried to modify the storage settings for a number of her libraries. I attached her external hard drive, clicked Modify Storage Settings, and created a new folder on the external hard drive toward which I directed the Media and Cache. I also created a separate folder in the external hard drive to which I directed the Backup. But now virtually all of the libraries show "Missing File!" for virtually all of the clips in every movie she's made. I've tried to "Open from Backup" and get nothing useful. I've tried to go straight to the original backup folder and open from there. Again, it shows up "Missing File!" How can I recover my daughter's movies?? Thanks!