The Recycle Bin has saved our lives on more than one occasion. It allows you to undelete any page or module you've deleted by accident or on purpose from the site.
Login with your Admin Account if you haven't already.
Mouse over the "Admin" menu item at the top of the screen and select "Recycle Bin".
In the Recycle Bin, you will see lists of both Pages and modules. You must restore the pages and modules separately from each other. You cannot restore a module from a deleted page without restoring the page it was on first, however. Choose the Pages or Modules tab to restore, and click the name of the item to be restored in the list. Then click the "Restore Selected Page" at the bottom. That page should be restored in it's original location in the menu, or a module back to it's original page when recycled.
It is never necessary, but if you build up many items you know you'll never need again, you can empty your Recycle Bin by hitting the "Empty Recycle Bin" button at the bottom. This will permanently delete any pages and modules found here.