Purchased apps lost after Apple ID change
Sorry but purchases are tied to an apple id and currently Apple does not provide a way to merge Apple ID's.   However since Apple changed your id without your permission then they may help you out.  Best thing to do is call Apple and ask why the Apple ID was changed.  

This comes right from Apple's faq page (http://support.apple.com/kb/ht5622) about Apple ID's:


  Apple IDs cannot be merged. You should use your preferred Apple ID
  from now on, but you can still access your purchased items such as
  music, movies, or software using your other Apple IDs.