We were in another location when I bought two new Kindle books, and they have never shown up on my Kindle. But the web site says repeatedly they have been delivered. What to do?
Sometimes if you're not in a good wireless zone when books are sent, they don't show. They're in your account on Amazon, just didn't make it to your device. (Assuming the connection was good enough that the purchase did go through.)
Another thing that can happen is that the 'default device' has gotten changed. If you've got more than one device registered -- whether Kindles, Kindle apps (on phones or tablets), or Fires -- you can specify which is the default. Anything you buy should go to that device. Sometimes, for no reason I've been able to determine, that 'default' gets lost and it reverts to the first device listed as the default.
If you buy FROM a device, it does normally go to that device vs whatever you have as 'default'. Though if you're on a phone, tablet, or Fire and you go through the browser, vs the Kindle app to the store, then any book bought should go to the specified default device.
Regardless of why it glitched, you can always find all your books on Amazon by logging into your account and going to Manage Your Kindle And Devices. There you can select any book to be delivered to any registered device. You can do a lot of other things there, as well. If you've not explored the page, it's worth a little time to do so.
If that doesn't seem to be working, there are some things you can try on the device.
First, turn wireless off and then back on again and let it re-connect. It's supposed to automatically, but a stray bit or byte could have knocked it off line.
Send, if it's a WiFi device, try re-entering the Wifi password. Even if it's a WiFi/3G device, remember that it wants to use WiFi as a default. AND, Amazon may not deliver particularly large files via 3G. It won't send system updates that way, for example.
Third, restart the device: go to settings/menu/settings/restart and let it shut itself all the way down and then re-boot. That will almost always clear any glitches.
Fourth, Un-register the device from your account and then re-register it. With this issue, if a restart doesn't work, sometimes that serves to refresh the connection.
If none of those things work, no matter the order you do them, the 'nuclear option' is to reset the device to factory defaults and start over. But that will, of course, remove ALL books and personalization. You'll be back to what you had when you took the thing out of the box. Before doing that, I'd try everything else and probably contact customer service to see if they have any other ideas.