If i want to develop a simple word recognition of elvish words, where should i start ? I have read many articles, but they are all about speech recognition in English language and not for custom language.
You might consider a visit to Voxforge.com. There you will find tutorials, a discussion forum and audio repositories relating to various languages. The tutorials are based on a fairly old but reliable set of tools and techniques including HTK, Sphinx, Julius and so on.
The tutorials are for English, but they are easily adapted to other languages. Your challenge will be to decide on a set of phonemes that will apply to Elvish, produce a set of audio samples in that language, then build the model. With the correct phonemes and sufficient audio there is no reason your effort would not be successful, but it will take some time.
All the tools involved are open-source. The process is a bit involved, so if you are unfamiliar with the theory or process then you would be advised to do an English model first to get a feel for the possibilities, then do the more challenging foreign language which will be the same process but with different data.