Originally Posted by KimberlyFDR
Just wanted to follow up to say that de-registering and re-registering solved the problem! All my collections came back, along with the 400 files I had on it. It also seems to have sped up my Kindle navigation between files (used to have about a 5 second delay when I went into a file and then came back out). Thank you both for your help!
Happy to hear you fixed it!