Rejection...Criticism...the things we all have in common.
The 'R' word is a tough pill to swallow, however we have all heard it in some form or another. But as a writer, trying to get out into the world, trying to get noticed; that word hurts to the core.
This is your baby that you've been working on for what feels like YOUR ENTIRE LIFE. You finally have it completed and you think "now is the time that it will get picked up, put on bookshelves, and sold. Later a movie deal." Then the emails come back and it's not turning out how you thought it would...but let's face it; life never does. Get the chocolate, the wine, the 'whatever makes you happy' stuff out of the way and dust it all off.
People get rejected every day, but there wouldn't be success stories if those people didn't move along. Research the heck out of query letters and see what exactly you might be missing, find peers to glance over what you have and see if they notice something, or maybe...that specific person that you sent that query to, or those multiple people; they aren't the ones for you.
Do the research, if you feel you have done all you can in that avenue- change your path. There are publishing companies out there looking for you. Or of course, the ever-growing Self Publishing biz is always ready for a new face and new story. Don't let this one time, or even handfuls of rejections let you stop from following your dream. You'll get there, but only if you push yourself. It takes time, effort, a solid foundation to find your footing on this massive adventure. Don't let it get away from you.
Just remember, Harry Potter was rejected 12 times before J.K Rowling found success!