try spraying a little wd-40 in the end of the bar, then thread the bolt in about half way, give it a tap with a mallet and it should loosenen up, then pull out with a pliers on the head of the bolt.
This will work great assuming the nut on the backend is still there to thread onto. If it's not a captured nut you can take a small toggle bolt and slip it through the hole and pull it out using the method mentioned.