If you made this in the guest world, it's probably gone by now. The guest world resets every few hours. Since you've joined the forums, you can go to the member world now. They don't reset, and there is less grief. Also, another helpful thing is to take screenshots so we can see your creations on the forum without having to go ingame. To take a screenshot, press the Print Screen button on your keyboard. Then, open Paint and press Control + V. Crop the image so that it only shows the Minecraft window, then save the picture on your computer. Finally, upload the picture to imgur.com and copy the BB code link and paste it in your topic. Or, if you're using World of Minecraft, press the screenshot button, then upload the picture it takes.
I hope this helps!