I wish there was a restore function, but there isn't.
I wrote to Amazon, pretty much what I posted above—wanted to sure they understood how unhappy I am. I got a canned response:
QUOTE
Hello,
I’m sorry to hear the disappointment you had with your Kindle Paperwhite due to the latest update. Also, I can understand that how frustrating this would be for you as you’re not able to use the Kindle properly. We're regularly working on improvements to your Kindle experience.
Please be assured that we're continuously working hard to improve your Kindle experience. In addition to our large selection, one of the benefits we try very hard to offer our customers is convenience.
Therefore to make sure that your comments are heard by the appropriate people in our company, I have forwarded your comments, expressing your displeasure and the disappointment over the poor Kindle experience to our management department and please be informed that they can take notice of your comments and take appropriate action in this issue and make sure that this won’t happen in future.
We truly value this kind of feedback, as it helps us continue to improve our store and provide better service to our customers. It is always important for us to hear how customers react to all aspects. Customer feedback like yours helps us continue to improve the service we provide, and we're glad you took time to write to us. The Kindle Team will carefully review your message.
I hope that you will honor us with another opportunity to prove the quality of our service to you in the future. In addition to a wide selection of items, one of our aims at Amazon.com is to provide a convenient and efficient service; in this case, we have not met that standard.
We appreciate your understanding and patience in this regard. Please give us chance to serve you better in future.
Best regards,
From what I've read in the Kindle forum today, this mess happened to some people but not everyone; so it appears to be a nice bug. Supposedly Amazon is working on a "fix", with no release date set. Right. It'll happen just about when I get this cleared up on my paperwhite.
I've now recharged my old Kindle and am using it. Not the same, but beats the mess my paperwhite has become.
"Quality takes time! Sloppiness, not so much..." J. P. Bezos
HA! I'm gonna insert that in my next complaint, which I'm now working on due to NEW issues.
I'm horribly frustrated, and yet in the scheme of things this isn't important, other than I rely on my Kindle while at the clinic.
How
do you back up that device, anyway? Automagic on Amazon's servers?

Books purchased from Amazon are stored on their cloud and "always"
available.
Any other way of backing up my ebooks is not allowed, and so I would never do any of those things.
So, it doesn't have apps. Like Contacs, rememberers, to do lists, interweb surfers or the all important things like Twit and FacePoster?!
No. The paperwhite is an eink book reader, not one of the tablets.
Update: new paperwhite is defective!
Screen has scratches and is filthy! I can load books onto it, but not remove them. Books open with errors that this book was for a different Kindle and to download it again; but I can't do that because I can't remove it—and I loaded the books direct from Amazon's site.
I need a blowing my top smilie.
Kimmer, I load Kindle books on my iPad all the time. There's an app for that.

But I suspect you know that.
There are various alternatives to Aldiko for the iPad as well:
http://alternativeto.net/software/aldiko/?platform=ipad
Thanks for the link. My problem is that the iPad is a shiny screen (Retina display?), and not an eink screen. That's what Apple needs to come up with for me.