My illustrator designed the cover of my book, but my publisher did not want to use his cover. They wanted their illustration department to do it. What I didn't know was that they copyrighted the cover and the interior of the book. Does this mean I can't use that cover or my illustration ever again?
Normally you are the automatic copyright holder of original content, and assign publication rights (territory, language and media-specific) to a publisher or publishers for an agreed period. The publisher's copyright would extend to the layout and design, I would have thought, unless the contract has been drawn up to assign copyright entirely to them. Check your contract terms.