SQL Server schema intact but every record from every table is gone
This happened at my company.

Someone re-ran the schema creation scripts from within the application's admin interface--something like an "initialize database" command. These scripts included a series of IF EXISTS()...DROP...CREATE statements to drop and recreate each table and constraint. Since they were designed to wipe a database even if it was already populated, they were carefully structured to account for foreign key relationships. Thus, the database schema was there and looked great, but all of the data was gone.

To prevent this, revoke the appropriate DDL permissions from the app's database login after it has created its own schema, or make sure any "initialize database" functionality your application has includes several safety checks and presents appropriate warning to the user regarding what's about to happen.