I have the book of Kaza and i dont know what to do with it. Is there something to do with it instead of selling it ???

No, flog it whenever you can. For a book, it sells for quite an impressive sum.

i think i remember meeting someone or something in the crypt that said the book was important. i only remembered it when i read this post so i don't know if it anything. he was in the corridor that branched off before the room were the book was supposed to be.

No, that's Edwin's Nether-Scroll quest. I'm pretty sure the two are mutually exclusive.

that why i couldn't do the nether-scroll quest!!!

Get Edwin to talk to the lich. The two will get into an argument and you'll need to fight it. When it dies, Edwin will pluck the nether-scroll off its corpse, and that will be that. For a while, at least. Then Edwin will... ah... well, I'll let you find out for yourself.