Mine happend the same thing, no clue what went wrong but I managed to get it back working by following https://sakimichi.wordpress.com/2014/03/21/vnreader-advance-guidetutorial-part-1/ Sakimichi instructions on the comments
They where:
Delete the files Unidic in your Visual novel reader folder. It’s in:Caches/Dictionaries/UniDicthen download :http://sakuradite.org/pub/unidic/unidic-2.1.2.tar.xzExtract all files inCaches/Dictionaries/UniDic
Restart VNR and you’re good to go~