What should I do if my final year project supervisor does not answer my questions
Email is a terrible way to supervise work for both parties involved.  It's difficult to ask a good question over email and it's difficult to address a misconception over email.  From your question, there's no way of knowing which of several types of problems you are experiencing with your advisor.  The answer to all of them, however, is to have regularly scheduled meetings that are face-to-face if possible, or over a video link if you are doing distance learning.