Calmly, you settle in and check the server and eventually find your way to the error logs to see the following:
Msg 823, Level 24, State 2, Line 1
The operating system returned error 1(Incorrect function.) to SQL Server during a read at offset 0x0000104c05e000 in file ‘E:\Database\myproddb.mdf’. Additional messages in the SQL Server error log and system event log may provide more detail. This is a severe system-level error condition that threatens database integrity and must be corrected immediately. Complete a full database consistency check (DBCC CHECKDB). This error can be caused by many factors; for more information, see SQL Server Books Online.
Suddenly you understand and feel the collective fear and paranoia. What do you do now that the world has seemingly come to an end for your database?
Definitely worth a read.