Start iPhoto with Option and Command held down, Rebuild thumbnails.
The question is why? are you deleting photos from Finder, which is taking them out of your iPhoto Library? Always use iPhoto to remove photos from it's library.
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.