I'm having a similar problem. I can't see the link bob mentioned, but I don't know if it's me or if, perhaps, because the original query is classed as resolved or because certain info was only visible to the person to whom they're responding. Maybe it's because I'm using a tablet (Fire 8.0) rather than a PC.
Also, if anyone has had this problem, do they know whether when I contact Amazon I need to be able to give them a list of all the missing books or whether I can simply request that they reinstate any permanently deleted items?
Keep in mind that it's up to whomever you contact at Customer Service as to whether or not they will add any deleted books to your account. They do not have to do undelete them especially since there is a clear warning that deletion is permanent.
Also, make sure that you have the invoices on your account for those books. All too often a customer changes their email on the device instead of changing it on the account and will thus create a new account and in that case the books are still available but under the old account. In that case, simply linking the two account through Family Library will enable you to download the books.
and yes, you're probably better off having a list available when you contact them. Don't use email as it's more likely to receive a "sorry, you're SOL" email in return. When compiling the list, you can also check the order number.
ETA: Bob's link goes here:and goes to the UK Amazon site
Help (link o bottom of page)
Need more help?
ETA2: often Amazon will reinstate 2-3 books but not dozens or hundreds