photo album empty but can't delete it...

Hi-today I put last years photos on an external drive and deleted the photos off of iPhoto. I have 2 folders (Nov & Dec 2011) that are empty but I can't delete them. It says that I have to delete the Aperature pics in them first. I don't have or use Aperature and have gotten no photos from anyone from Aperature. How do I get rid of them? Also, there are some folders that show no albums but I know I created them-they are just not showing up-how do I get iPhoto to show the albums? I have Events for each one. Thanks! Judy