Another frightening reminder that modern digital media and Digital Rights Management are horribly done.  Amazon, in this case, have replaced customer service with theft.  That rots.  

If you need to have an e-reader, try one that uses EPUB electronic book format.  EPUB is open source, retailers can still use DRM, but you can also find a ton of free books all over the internet in EPUB format.  If you can live without the current bestsellers, if you like classics, if you like exploring books in the public domain, EPUB is for you.  It will work with any number of software options, and you can read it easily on your Nook, Sony E-Reader, Blackberry, iPad or iPhone, and lots of other devices.