Gahh, I did the same exact thing when I started out! Took me forever to get all of it back. Turns out that you can click the buttons in the Home tab at the top to bring them up again -- the Layout, Project, Properties, Objects, and Animator tabs will all be back where they should be.
Alternatively, I think deleting the persist file will have the same effect. The Persist file saves settings for you, like where you placed the tabs and such, so everything looks the same when you open up the cap file again. If you delete the persist, everything will go back to its default settings.
Hopefully one of these will work out fine for you. Don't worry about the mistake -- like I said, I did the same thing.