You've followed all the proper steps of protocol — wrote the story, polished to your best ability, had it professionally edited and submitted it with a query letter, as requested — OR, submitted a query letter, in hopes the response will be a request for the story.
You received a thank you, no thank you AKA a reject.
What went wrong?
Perhaps it was your query letter. Let's look at some of the possibilities to garner that reject.
Okay, first mistake: To Whom It May Concern. Beginning a query with an impersonal salutation to anyone who happens to pick it up will NOT bring a warm fuzzy to the reader. If you don't know to whom to address the query letter then do the research and find out. Even a "Dear Sir:" to Ms. Miller is going to get your start off on the wrong foot. If need be, call the establishment and ask to whom the letter should be addressed as a last step. The internet is a great resource and if that doesn't reveal what you need, check out the library for current versions the Writer's Digest "Writer's Market" or a copy of the magazine with editor information listed. Do your research!
Secondly — Comparing your novel to a best seller or a group of best sellers is completely off the chart. Trust me on this, the publisher will decide if your grand piece of work will be the next blockbuster or world-wide seller. Instead, define your work in such a way as to ascribe possible similarities to those best sellers more subtly.
Thirdly — You didn't. Never EVER tell the potential publisher that your mother loved your tale. Of course she did, she is your mother. This is the sign of an amateur. Let the publisher decide if the story is that great. You could have two thousand people waiting to give it a 5-star review on Amazon but it doesn't mean the story is good. It means you have two thousand friends willing to help you. Just like never have your family and/or friends edit the story - never use them as endorsements - unless of course they happen to be somebody with clout to ensure the endorsement will carry weight. In other words, unless your parent, relative or close friend is Martha Stewart, Steven Spielberg, President (past or present) of the United States or Neil Armstrong, don't bother mentioning them, they don't count.
Finally — Don't be pretentious or pushy. Let them decide if they want to offer a contract. Otherwise you've set yourself up for a horrible let-down because more than likely, there won't be a contract forthcoming - if they even read the submission.
So what DOES go into a proper query letter? Read the guidelines. The place in question may have particular guidelines for submitting including style, font, information wanted. Some may request a simple paragraph defining your work, another perhaps only a single line. To help you with your query letter, before you start, take the time to describe your story, even if it is a three-hundred page novel, in one succinct sentence. Find the essence in one sentence, you can always expand/expound on it to make a paragraph. Follow the guidelines, if available, and always, ALWAYS be professional. You are an author and this is a business, not a hobby.