I go get a fresh copy from either my backups (backup today is not optional as PCs and such are not reliable.) Or from the place I got it from. I've never had to recover a corrupted PDF or such, because backups and can get a fresh copy.
I bought an E-book but I must have done something because I now find that there are sections of the content that have changed colour where parts are red and green. What is worst is that those sections have a line running through the middle of the sentence. Does any one have any idea if the download is recoverable?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic