The name of a fantasy story whose end loops back to the beginning?

Question

I am looking for the name and author of a late 80s/early 90s fantasy/sci-fi story whose ending loops back to its beginning due to "time damage". Our hero, at the end, is about to begin the plot all over again, thanks to "time problems". It is a fat book.The flyleaf notes "references" to *Finnegans Wake*. I never finished the book, but from the beginning the "time damage" problems are apparent.

Answer 1

You're not thinking of Stephen King's Dark Tower series, are you? That's the only thing I could think of.