1) The recommendation to use Restore by Media was given as a way to see if the problem is Database related and not as a solution.
2) He backed up only one file. We are not trying to get this particular data restored, as much as we are trying to resolve the failure to restore in general.
3) The failure is on the session header, if it gets past that then we know there is a problem in the database.
4) What if it is not Database related then he just wacked his database for no reason.
5) A Filter can always be used with Restore by Media, so there is no need to restore the whole session.
By the way it would be a good idea to see if verify also fails. If verify does fail, and if it is not Database related, and if the updates do not help, then a put the Job and Tape Engines in debug and run the one file backup again with Verify Compare Tape to Disk. Those logs should help to find the source of the problem.