If it can't be seen at all in the Google index it could be one of three reasons:
If its a new website it may still be being validated by Google.
If you've received a Google penalty then it may be removed from the index.
If Google doesn't think its good enough to be in the index, it won't include it.
If its just a matter of not ranking on page 1 where you want it to be then it will be because other SEO experts are doing the SEO better than you. If you want a professional SEO consultant to take a look then get in touch today.