Dragon, Gateway, and Overworld Portal absent

When I finally got into the End, I noticed there were was no health bar above for the Ender Dragon. As I explored the island, the portal to the overworld was also missing. So I am practically stuck in the End unless I die. The only thing that was not absent were the obsidian pillars. The crystals are still there and still explode, but serve no function since there is no dragon.