Book Store and Audiobooks wont load in ‘Books’ on iPad

On Tuesday January 21, I purchased two books through “Books” on my iPad (running iPad OS 18.1.1). Since then I have been able to access “Home” and “Library” but not “Book Store” nor “Audiobook Store” — I get a blank screen and the “waiting” icon.

I need to access the Book Store in particular (but would also like to buy a specific audiobook). What is the problem, and more importantly, what is the solution — other than going to a physical book store and buying the voluminous paperback editions.

[Re-Titled by Moderator]