I bought books and now I cannot find them. I deleted them now I want to download them again

If they don't show in the Purchased tab in the iBookstore in the iBooks app for redownloading then have you checked to see if you've hidden them from the cloud (audiobooks can't be redownloaded without re-paying for them) : Hide and unhide purchases in iTunes or iBooks on your Mac or PC - Apple Support ?

If they are no longer in your country's store, or if you've moved countries since buying them, then you won't be able to redownload them, you will have to copy them back from your backup of your downloads/library and sync them back to your iPad.

why is it that if one moves from country that one cannot redownload. Ridiculous in my opinion. One has purchased the book and the agreement states on can redownload it later if one is deleting or hiding or moving to the cloud ?

Licensing, a book (or album, film etc) might have different rights-holders for different countries.

One has purchased the book and the agreement states on can redownload

The store's terms, which you read and agreed to, state that you might not be able redownload items and to take a backup of them

Thank you for sharing your comments about iBooks. The license deal makes total sense .Is it a matter of concern that the purchase is not available at the moment in iBook store (same country and apple user account & store originally purchased) for redownload ? My dilemma is the book I purchased doesn't appear in my hidden books the cloud or list of purchases.What would be the reason in your opinion.I respect and appreciate your comments because you seem very well versed with iBooks and that is why I am here searching for an answer,Thank you once again/

It's possible that the publisher/rights-holder has removed the book from your country's store, possibly because they've now done an exclusive deal with a different ebook store.