I doubt that reformatting the drive was a good idea, though I'm not technical enough to understand what that will have done. Have you tried a hard-reset of your Kindle? This link gives you the details of how to do it, plus a video:
http://www.amazon.co.uk/gp/help/cust...deId=200996540
In summary:
"Restarting your device can sometimes resolve issues like a frozen screen or problems downloading content.
There are two ways to restart your Kindle Paperwhite:
1.From the Home screen, select Menu , and then select Settings.
2.Select Menu , again, and then select Restart.
If your device is unresponsive, you can also restart it by pressing and holding the power button for a full 20 seconds. You will see the screen flash after several seconds; this is normal.
Keep pressing the power button for the full 20 seconds. When the restart is complete, you’ll see the start-up screen.
Restarting your Kindle may take a few minutes to complete."
If your Kindle is frozen, the second option is the only one open to you at this time.