How do I recover photos lost by iPhoto. I tried using Time Machine but I get an error message saying that I don't have permission.

IPhoto quit in the midst of importing some photos to the library. When I reopened it, it had some events, that were imported a few days earlier, which had no photos. They were missing. I tried Time Machine to restore the iPhoto Library to a version made a couple of hours earlier. But I got an error message saying that I did not have permission. I tried restarting iPhoto while holding down the Option key and tried to access the Time Machine iPhoto Library, but that only got me a portion of the library and not the portion that was missing earlier. When I restarted iPhoto this time, even more of my photos were missing.