After backing up to an external drive all I see is MEDIAID.BIN 1KB. Where are the files stored?

was this a data backup? If it was a complete PC backup you should see a disk icon. That file is part of the backup. There should be another folder. did the task complete successfully? Start a restore data and point it to the media where you backed up when it asks. Does it find a backupfile? If not, the backup failed.