iphoto view changed and i cannot change it back. lost sidebar and main landing view. what to do?

i accidentally hit something on my MAC and it changed the view of iphoto. The sidebar and main view is gone and I cannot figure out how to get it back. please help!!! i cannot export photos or do anything with it. some of the actions are along the bottom but I can't see any of the detail or actions on the sidebar or above ribbon.