My son pulled out the USB cable while iPhoto was running from the external hard drive and a message came up when I plugged it back in that said there were inconsistencies that needed to be repaired. So I followed the instructions to complete it but it didn't work.
Next I used a new external hard drive to make a back up of the MacBook and a copy of the iPhoto Library.
Then the iPhoto Library msg said that it was either being used by another user or unreadable. I saw that there were 4 other options if you opened iPhoto while pressing command-option.
Once copied I tried to open the copy but kept saying it was unreadable still. Restarted etc., didn't work again. Tried the first option, repairing permissions... didn't work, next tried option 3, but then the message came up saying that it would only be available once Time Machine had finished. But Time Machine isn't on!
I'm not sure what to try next.