A page has been deleted from the portal and the customer would like the page recovered from backup.

First, we need a backup of the database from a time when the page existed, preferably from the day before it was deleted. Restore this database to the same SQL server under the name Passageways_Restore.
INSERT INTO Passageways.dbo.PWPages
SELECT [ViewID]
      ,[PageID]
      ,[PageOrder]
      ,[DisplayText]
      ,[PrefString]
      ,[NumofCols]
      ,[IsPublic]
      ,[IsAppStartPage]
      ,[PageType]
      ,[TemplateID]
      ,[Tags]
      ,[FolderID]
      ,[CreatedByUserID]
      ,[CreatedDate]
      ,[PageTemplateID]

  FROM [Passageways_Restore].[dbo].[PWPages]
where PageID = '{PageID Here}'

INSERT INTO [Passageways].[dbo].[PWPageIslands]
SELECT * FROM [Passageways_Restore].[dbo].[PWPageIslands]
  where pageID = '{PageID here}'

After 6.0, also run the following script:

--Workgroup PageCSS
INSERT INTO Passageways.dbo.PageCSSAttribute
(Selector, Property, Value, IsImportant, PageID)
Select Selector, Property, Value, IsImportant, PageID from [Passageways_Restore].[dbo].[PageCSSAttribute] where PageID = '{PageID Here}'

Once finished make sure to refresh portal cache to reflect the new Database changes:

Portal Tools --> Manage Portal Framework --> Cache Manager --> Refresh Cache