About my ipad book apt you know the orange with whit book on it apt thingy?

I deleted almost 2k of ebooks to save space on my iPad to download new ones, and under my library tab I only see the small amount I downloaded new, but under my account tab section all book section it says I allmost have 2k books allready on it, why is that why can’t I see my 2k books or shows me in the account section all books tab on my ebook section?