I also facing to the same error. Actually my server (win2003) was corrupted when I was taking the backup. My Sql server is 2000 in it was in a Raid5 server. Finally I was managed to retrieve only the backup file, but unfortunately default SQL restore database restore gives me the below error:

link:https://www.sqlservercentral.com/Forums/Uploads/image-unavailable.png

Then, I used "RESTORE HEADERONLY " command and giving me below:

link:https://www.sqlservercentral.com/Forums/Uploads/image-unavailable.png

"RESTORE VERIFYONLY" command giving me the following:

Link:https://www.sqlservercentral.com/Forums/Uploads/image-unavailable.png

"RESTORE DATABASE" command giving me the below error:

link:https://www.sqlservercentral.com/Forums/Uploads/image-unavailable.png

Could you please help me?