Or a LB. Before you try to repull anything you need to inspect as much of the conduit run for damage or pull stations. Of course if it is all below concrete you can assume all bends are sweeps and you can pull away.If you are lucky, you can use the old cable to pull the new cable through. You will then be able to inspect the old cable and find out what happened.
One other thought- If each end does not want to move, there is always the possibility that there may be a splice or patch block that no one knows about, and may be where the problem is.