I recently had a problem with my MacBook Air. I went to Apple and they said they would fix it but all my data will get deleted. I said okay but when I got my MacBook back, I didn't know my apps would get deleted. Some of they apps were iMovie, Pages and Numbers. They were already installed when I first got the MacBook.
unfortunately, your apps are gone, or their saved date is. You can go to the app store's purchased section, and re-download those apps. Its advised to always make periodic backups of your computers Harddrive, so if something goes wrong, you wont lose much.
If you are running a new version of OS X, say El Capitan, you may have ICloud Drive, pages will automatically upload to your iCloud drive, you could check that, I have never used iMovie, but their is a possibility that it may also do as pages does.