It wouldn't have been deleted (unless it was offensive or violated board policies), so most likely it just fell back a page or two. Follow Peter's suggestion and when you find your post you can reply to it with "BUMP" as the message - that'll move it back up to the top.
Note that if you didn't get a response you might want to consider if you phrased your question well enough and/or gave enough background information for anyone to go on. Most of the time the answer you get is entirely dependent on the information you provide.
HTH,