For traditional publishing, you need a literary agent. To sign with one, you need a polished query letter. Those little one-page pitches are the toughest writing of all. Agents receive so many these days (electronically) they usually don't even respond unless their interest is piqued somewhat. It's very frustrating to be rejected over and over, but it's up to you to fix your query letter and keep trying. One of the differences between amateur and professional. Keep working at it, and you'll figure it out. Seek help from fellow writers and take their criticism and advice. With hard work, you'll get there.
Here is my two cents. A great query formula is this: An awesome log line to immediately grab attention. If it's not great, the agent will probably not read beyond this. Next, have only a couple of paragraphs with fantastic description of your book sprinkled with some plot points. Compare it to best selling works if asked to do so. Then, include a one-paragraph bio. Sounds easy, right? It's not, but practice makes perfect. Good luck!