Can i get a refund if I ordered wrong book on ibooks and cancel it please?

no you can not

Is it a book that you've bought or is it only a pre-order ? If pre-ordered then you can cancel the pre-order : iTunes Store: About pre-orders (you aren't charged for pre-orders until they are released, so there shouldn't be anything to refund)

If it's an already released book that you've bought then purchases are considered final, but you can try the 'report a problem' page to contact iTunes Support and see if they will refund or credit you : http://reportaproblem.apple.com

Or you can try contacting iTunes Support via this page : http://www.apple.com/support/itunes/contact/ - click on Contact iTunes Store Support on the right-hand side of the page, then Purchases, Billing & Redemption

Thank you. I followed the link to apple support, emailed regarding the fact that I purchased the wrong book and they responded and issued a refund within the hour. Problem solved.