[cloudkj]

This exact thing happened to someone I know. He got a call right as he was leaving his old job on his last day. The guy said something along the same lines - due to changing circumstances, the original position we were offering you has been eliminated. The guy was flabbergasted, of course, but just ended up going back to the old company anyway. I'm pretty sure if you want, you can get your job back. Unless you were leaving on bad terms or there's something more to the situation.

To make it a little easier, you can just join another team at the same company instead. That way it's a little less awkward.