The English language has a lot of silent letter words. It means letters that you can't hear when you say the word, but you can find it when you write the word.


 why there are  Silent letters? because difficulties for both native speakers and English learners. Also because they make the spelling of words different from their

pronunciation.


check this link it might help you 


http://www.espressoenglish.net/silent-letters-in-english-from-a-to-z/